Urko De La Torre

Jon Sertucha

Anna Regordosa

Jacques Lacaze
email: jacques.lacaze@ensiacet.fr

Effect of silicon on the metastable eutectic temperature of Fe-C-Si alloys

Keywords: silicon cast iron, metastable eutectic, solidification, tellurium

An attempt has been made to establish experimentally the temperature along the metastable eutectic in the Fe-C-Si system, down to the invariant three phase eutectic involving austenite, cementite and an iron silico-carbide. This was carried out by standard thermal analysis using cups with a coating rich in tellurium that is known to impede graphite growth. It turned out that evaluating the metastable temperature is possible up to a silicon contents of 3.8 wt.%, beyond which the driving force for graphite growth becomes so high that the development of stable eutectic cells can no more be hindered. This is quite unfortunate for melt control on the foundry floor but triggers further study for understanding and describing graphite shape in cast irons.

Introduction

Most cast irons are essentially Fe-C-Si alloys with low levels of additives or impurities.

Thermal analysis is used as part of quality control during the preparation of the cast irons prior to mold casting and various commercial systems are available. Thermal analysis can potentially be used to estimate both carbon and silicon content as described in a previous work for eutectic and slightly hypereutectic alloys (referring to the stable system) [1].

However, this possibility depends on the actual ability to avoid graphite precipitation and to complete solidification by the metastable eutectic whose temperature depends mainly on the silicon content. The previous study highlighted the limited knowledge of the metastable eutectic temperature in the Fe-C-Si system and the present study aimed to provide original and consistent data.

With the rather recent development of high-silicon cast irons, metastable silicocarbides (SCs) may appear along with cementite, either during solidification or by precipitation in the solid state. A comprehensive review of the literature on microstructures and corresponding phases was recently proposed by Kante and Leineweber [2]. In rapidly solidified alloys containing 3-11 wt.% Si, these authors studied the metastable two-and three-phase eutectic microstructures that could emerge. These observations were compared with the metastable liquidus of the Fe-C-Si system as predicted by the evaluation of Lacaze and Sundman [3] and the recent assessment of Miettinen et al [START_REF] Miettinen | Thermodynamic Description of the Fe-Al-Mn-Si-C System for Modelling Solidification of Steels[END_REF]. The two calculated liquidus projections are superimposed in Figure 1-a, where good overall agreement is seen with differences starting at silicon content higher than 5 wt.%, due to the fact that the assumed SC formula was not the same, i.e., Fe 8 Si 2 C for the former evaluation and Fe 6 SiC for the latter. Interestingly, the Miettinen et al. assessment reproduces a broader set of experimental information than the first assessment that was focused on the low silicon domain.

Figure 1-b is a projection of the stable and metastable eutectic lines on the temperature-silicon content axes. The metastable cementite/austenite eutectic is located a few degrees below the stable eutectic in the Fe-C binary system, and is easily reached at limited cooling rates due to the slow growth kinetics of the stable graphite/austenite eutectic. With the addition of silicon, the temperature difference increases to nearly 100°C at 5 wt.% Si, which is the upper limit of current silicon cast irons. Reaching the metastable eutectic is therefore increasingly difficult and can be achieved either by increasing the cooling rate or by preventing graphite nucleation and growth. Kante and Leineweber relied on the effect of cooling rate and indeed obtained predominantly metastable microstructures. However, they reported that graphite precipitates were present in their castings in amounts that increased sharply with silicon content. Thus, the real possibility of changing completely from stable to metastable solidification by increasing the cooling rate has intrinsic limitations. For the present study, the alloys were cast in commercial thermal analysis cups containing tellurium which is known to inhibit graphite growth [START_REF] Nieswaag | Solidification structures and graphite patterns in telluriumtreated grey cast iron[END_REF][START_REF] Tsutsumi | The influence of tellurium on the graphite formation of cast iron during solidification[END_REF]. A series of experiments was performed where a base melt with 1 wt.% Si was prepared and gradually enriched to 5.64 wt.% Si. Thermal analysis showed consistent results for silicon contents up to, but not beyond, 3.8 wt.%. Metallographic analysis was performed for high silicon samples to determine their solidification microstructure and to clarify the limitations of this technique.

Experimental details

The objective during the trial was to maintain a melt composition close to the stable eutectic while the silicon content was to be increased by steps of 0.2 wt.% from 1 wt.% up to 6 wt.%.

For this, a melt was prepared in a 100 kg capacity medium frequency furnace (250 Hz, 100 kW) with a metallic charge made up of 30 kg of low alloyed ferritic ductile iron returns and 40 kg of low alloyed steel. The carbon and silicon contents were adjusted using pure graphite and FeSi75 master alloy, respectively, and the first melt contained 3.88 wt.% carbon and 1.04 wt.% silicon (see table 1). Further increase in silicon was achieved by adding an appropriate amount of FeSi75 alloy according to the metallic mass present in the furnace. During the test, the decarburization of the melt by reaction with oxygen due to holding in the furnace and the relative decrease in carbon content due to the addition of FeSi75 were expected to ensure a steady decrease in carbon content so as to more or less follow the stable eutectic line (see Figure 10-a).

The furnace was kept at low induction power to maintain a near-constant temperature of 1450ºC, which ensured reproducible casting conditions throughout the test. For each composition, a medal sample for subsequent chemical analysis was poured, as well as five standard cups for thermal analysis (TA) in which a Te-rich patch was glued. The two types of cups available from Heraeus Electro-Nite are shown in Figure 2, which have the same external shape but with a square (SQ) or round (RD) cavity whose dimensions are listed in the legend to Figure 2. Repeat samples poured into the same type of cup were used to assess repeatability. The gray spot at the bottom of the cavity is the Te-rich coating. During the course of the test, the appearance of recalescence at the 4.49 wt.% silicon content (casting 18) led to the replacement of some of the single Te-coated cups with double Te-coated cups. The SQ double-Te cups were supplied by Heraeus Electro-Nite while the RD double-Te cups were prepared by hand gluing a second Te patch onto the existing one. In the following sections, the samples will be referenced by two numbers separated by a dot, the first number being the melt number (1 to 22) and the second indicating the type of cup (2 and 3 being RD, and 4, 5, 6 being SQ). For a single Te coating, independent measurements have shown that the maximum amount of tellurium transferred to the melt is on the order of 500 ppm, but that the amount remaining in the melt decreases rapidly if the tellurium is not tight in compound form [START_REF] De La Torre | [END_REF].

All medal samples were analyzed using a combustion technique (LECO CS300) to determine carbon and sulfur content, while spark spectrometry (SPECTROLAB) was used to determine the content of all other elements. In the case of silicon, however, spark spectrometry was replaced by a gravimetric method for contents above 3 wt.%. The compositions of the alloys prepared in this work are listed in Table 1 where it can be seen that a maximum silicon content of 5.64 wt.% could be achieved. It is also noted that the only element other than Fe, C and Si, which showed a non-negligible content is Mn, although at a low value of 0.13 wt.%. The cooling curves were recorded using a data logger and a few examples are shown in Figure 3. All curves showed two thermal arrests, a short one that corresponds to austenite formation (denoted T LA in the following) and then a longer one that relates to the eutectic reaction. Metastable solidification recorded by thermal analysis is generally associated with a flat horizontal plateau [8,9], as reflected in the curve of sample 17 in Figure 3. This is due to the fact that the solidification front progresses in a columnar shape from the outer surface to the central part of the sections, with latent heat being removed by the solid rim [START_REF] De La Torre | [END_REF]. In some rare cases, such as sample 6 in Figure 3, the plateau is almost flat but with slightly decreasing temperature. In this case, the temperature considered as characteristic of the plateau is that for which the time derivative of the curve is maximum. For high silicon contents, the cooling records showed a recalescence as illustrated by the curve of sample 22 in figure 3. In this case, the eutectic transformation can be characterized by the minimum temperature, T e,min , before recalescence and the maximum temperature, T e,max , reached during recalescence.

The temperature considered as characteristic of the eutectic transformation is that of the flat plateau in case of no recalescence or T e,min in case of recalescence. This choice is highlighted by the short dashed horizontal lines in Figure 3, and these temperatures will all be referred to as T e,min in the following for ease of reading.

Results

The curves were all analyzed to evaluate, T LA , T e,min and recalescence Rec (Rec=T e,max -T e,min ), and all values are listed in Table AI in the appendix A. The values of T e,min and recalescence have been plotted in Figure 4-a as a function of silicon content. For silicon content up to 4.21 wt.% (alloy 16), the data from all five cups show high consistency with T e,min dispersion limited to less than ±1.5°C and no or very low recalescence. The transition is best seen in Figure 4-b which is an enlargement of Figure 4-a for the high silicon content range. At 4.28 wt.% Si and above, the T e,min values evaluated with the 5 curves for each alloy become more dispersed and significant recalescence appeared for some of the records at 4.49 wt.% Si (alloy 18) and above. Since this behavior is generally associated with the growth of stable eutectic cells, it was decided to also use double-Te cups for subsequent casts. In any case, almost all records showed significant recalescence for silicon contents above 5 wt.%, with some values reaching 30-70°C.

Thus, a clear transition was observed with increasing silicon content, with first a dispersion of T e,min values from 4.28 wt.% Si (alloy 17), and then an increase in recalescence values from 4.49 wt.% Si (alloy 18). The question therefore arose as to whether the appearance of SC could explain this behavior, especially in view of the very high recalescence values that were reached and which would normally indicate that eutectic solidification took place in the stable system. In the Appendix B, it is shown that SC could indeed be detected but at low levels in agreement with the results of Kante and Leineweber [2] for silicon contents such as those of A first step in understanding the effect of increasing silicon content was to observe the microstructure of alloy 16 with 4.21 wt.% Si. As shown in Figure 4-b, all cups cast with this alloy showed very little recalescence and their microstructure should be similar. Figure 5 presents the microstructure of sample 16.5 chosen as an example. Unexpectedly, Figure 5-a before etching evidences quite a large amount of graphite, indicating that many stable eutectic cells have developed, while the many carbide plates left white after etching in Figure 5-b demonstrate that much of the eutectic solidification has, however, taken place in the metastable system. Considering now the cooling curves that displayed recalescence, Figure 6 shows the five records for alloy 18 (Fig. 6-a) and for the last alloy 22 (Fig. 6-b). For alloy 18, the recalescence is still quite low for the three records with RD cups while it is already significant for the two records with SQ cups. The micrographs of sample SQ 18.3 are presented in Figure 7, before and after Nital etching. The first shows significant graphite precipitation between a dendritic structure, while some plate-like carbides are easily observed after etching. The microstructure of the other SQ sample 18.2 which showed a similar recalescence was identical. It can be inferred that all three RD samples of alloy 18 also had graphite, as was the case with sample 16.5 in Figure 5-a. The cooling curves of alloy 22 at 5.64 wt.% Si all showed significant recalescence that was minimum for double Te-coated SQ sample 22.2 whose microstructure is illustrated in Figure 8. From the micrograph before etching (figure 8-a), it could be concluded that the microstructure is essentially graphitic but some carbide plates were observed after Nital etching (figure 8-b). In contrast, the simple Te-coated SQ sample 22.3 did not present any carbide. From these two samples, it would be concluded that the use of double-Te coating was effective in decreasing graphite precipitation and thus recalescence in SQ cups. However, Figure 6-b shows that this did not prevent graphite growth in RD cups as they all three showed huge amount of recalescence.

Discussion

From the metallographic observations presented above, it is concluded that recalescence of high-silicon alloys is related to precipitation of graphite/austenite eutectic cells and not related to the formation of a SC. In a previous study on thermal analysis of cast irons with silicon content of less than 3.8 wt.%, it was proposed that a record would still be valid for evaluating the metastable eutectic temperature if recalescence were lower than 5°C [1]. For such low recalescence values, it was understood that only a few cells of stable eutectic have nucleated and grown in the liquid ahead of the metastable eutectic front. Their number was however not large enough for the associated latent heat release to affect the metastable eutectic temperature indicated by the eutectic plateau. The question then arises whether this criterion can be applied to the higher silicon contents studied in this work. temperatures for each alloy. These two sets of results were therefore selected for further discussion and Figure 9-a shows the effect of silicon content on T e,min as in Figure 4 but here considering only these two cups and records meeting the above criterion. A regular and close evolution of the values is observed for these two cups, even for high silicon contents. In this figure are also shown the data evaluated in a previous work which was limited to 3.8 wt.% Si [1]. For silicon contents below 3.5 wt.%, the previous and current data sets agree well with each other. However, nearer to 4 wt.%, the previous data suggest a steeper slope with increase in the Si content than the current work. The present results would thus be at change with respect to the predicted evolution (see Figure 1-b) while older results are in line with them [1]. This discrepancy is illustrated with figure 9b where the decreasing solid line represents the metastable austenite-cementite eutectic temperature in the Fe-C-Si system as calculated with the TCFE8 databank [START_REF]Thermocalc softwares and databases[END_REF] that ends at the three-phase austenite-cementite-SC eutectic at 1074.4°C and 4.5 wt.% Si. The occurrence of this invariant eutectic is emphasized with the horizontal solid line in the graph. Note that this temperature for the three-phase ternary eutectic is slightly lower than the one appearing in original assessment [3]. Like any eutectic, the growth of the austenite-cementite eutectic takes place with some undercooling. An average value of this undercooling was estimated at 8°C by shifting the equilibrium solid curve downwards as represented by the dashed curve in Figure 9-b. Such a value agrees with estimate of the effect of cooling rate experimentally established by Oldfield and Humphreys [START_REF] Oldfield | [END_REF] that has been previously discussed [1]. The horizontal line representing the invariant ternary eutectic has been shifted by the same amount. It is seen that the present and past experimental T e,min values closely follow the dashed line up to the critical silicon value of 3.8 wt.%, but then diverge at higher silicon contents, while the few results

from the previous study at 3.6-3.8 wt.% Si do nicely fit with it.

The solid curve in Figure 9-b could be fitted by a second order polynomial of the silicon content, that was then shifted downwards by 8°C as in the previous work [1]. The temperature along the dashed line in figure 9-b that corresponds to the metastable eutectic as evaluated with a thermal analysis cup is thus given as:

(

It is interesting to note that the second-order equation proposed by Glover et al. [12] based on unpublished experimental data, for silicon contents up to 3 wt.%, predicts values very close to those given by equation 1. The small difference between the two equations is positive at 0.9°C for 1 wt.% silicon and negative at 1.3°C for 3 wt.% silicon.

Some ambiguity might have remained about the value of using the calculated metastable eutectic temperature as a reference for silicon contents above 3.8 wt.% if the microstructures of the samples had shown small amounts of graphite. On the contrary, the presence of significant amounts of this phase suggests that the offset of the measured temperatures from the dashed line is a strong indication that the records were in fact invalid. This is particularly troublesome for its two consequences:

-The criterion that was previously defined to validate a cooling curve to estimate the metastable eutectic temperature, i.e. that the recalescence must be limited to less than 5°C, is not valid for silicon contents higher than a critical value which certainly depends on the cooling rate and which is here estimated at 3.8 wt.%.

-Standard thermal analysis cups, even with the addition of tellurium, have no potential for the evaluation of the metastable eutectic temperature for a silicon content above this critical value.

On a more basic point of view, it is interesting to realize that tellurium is effective for favoring metastable solidification at low and not at high silicon content. This may be rationalized by evaluating the driving force for graphite precipitation as function of the silicon content. In figure 10-a is plotted the evolution of the composition of the stable and metastable eutectics in the composition plane (w C , w Si ) and the symbols represent the experimental alloys of the current work. It is seen that these alloys are close to the stable eutectic as expected, and that the carbon content in the liquid of the metastable eutectic diverges significantly as the silicon content increases. Figure 10-b shows with solid curves the evolution with the silicon content of the calculated temperatures of the stable (T EUT ) and metastable (T EW ) eutectics as well as that of the graphite liquidus for the carbon content corresponding to the metastable eutectic, noted . On this graph have also been reported the T LA temperatures measured during this work on cup 5. As expected, the T LA temperatures are found to be very close to the temperature of the stable eutectic, which has the interesting effect of ruling out the possibility that graphite nucleated as A value by excess of the driving force for graphite precipitation is given by the temperature difference between the graphite liquidus temperature when the metastable eutectic is reached and the metastable eutectic temperature, . Figure 10-b shows that this quantity does strongly increase with the silicon content. As a matter of fact, it is known that fully white structures can hardly be obtained at silicon content higher than 2 wt.% for usual casting conditions. The corresponding T value is 170°C, while further increase of the silicon content to 3.8 wt.% leads to T=350°C that can be considered as the limit beyond which impediment of graphite growth is no more effective enough for the cooling conditions experienced in thermal analysis.

It can be claimed that tellurium efficiently inhibits the growth of graphite up to 3% silicon, then restricts this growth less and less when silicon is increased beyond that value because the driving force T increases. While the cup is solidifying, cells of stable eutectic nucleate and grow just ahead of the metastable eutectic front moving from the outer surface to the center of the cup. At 3 wt.% Si, growth of the stable eutectic is limited because T remains relatively low and this does not affect the thermal record. On the contrary, at silicon content larger than 4.5 wt.% T has increased significantly and the growth of the cells of stable eutectic leads to recalescence and hence to an increase of T e,min above the metastable eutectic temperature. In the current work, the transition between these two cases occurred at 4.21 wt.% silicon (alloy 16) with eutectic plateaus that were flat but at a temperature that has been shifted upwards by the latent heat release ahead of the metastable eutectic front.

Conclusion

The description of the effect of silicon on the metastable eutectic by a second-order polynomial as previously suggested appears to be supported by the present work, even though valid experimental temperatures could not be measured for alloys with silicon content above 3.8 wt.%. This can therefore be considered as the upper limit for estimating silicon content based on standard thermal analysis. From a more fundamental perspective, the fact that tellurium can inhibit graphite growth up to and not beyond a critical undercooling below the graphite liquidus is of fundamental interest to better understand the shape and growth of graphite in cast irons.

Figure 1 .

 1 Figure 1. (a) liquidus projection of the metastable Fe-C-Si system and (b) Evolution of the stable and metastable eutectic temperatures with silicon content. Dashed and solid lines are according to Lacaze and Sundman [3] and Miettinen et al. [4], respectively. These figures have been kindly provided by J. Miettinen and V. Ville-Valtteri (bcc: ferrite; fcc: austenite; cem: cementite; gra: graphite; L: liquid)

Figure 2 .

 2 Figure 2. Upward view of the two different TA cups used in the present work: SQ cup (a) and RD cup (b). The grey patch at the bottom of the cavities is the Te-rich coating. The horizontal quartz tube protects the thermocouple whose junction is located in the middle of the cup. SQ cup cavities have a conical parallelepiped shape with a bottom base 35x35 mm, a upper base 37x37 mm and a height of 40 mm. The RD cups define a cylindrical volume with 34 mm in diameter and 40 mm in height.

Figure 3 .

 3 Figure 3. Records made with alloys 6, 17 and 22, cylindrical cup. The short dashed horizontal lines depict the eutectic characteristic temperature for each curve.

  2.1 wt.% Si #17 -4.28 wt.% Si #22 -5.64 wt.% Si the present work. Such small amounts could hardly support an alternative SC-related solidification pathway, and it was therefore decided to study the microstructure of alloys 16 to 22 quite systematically.

Figure 4 .

 4 Figure 4. T e,min and recalescence values as function of the silicon content for the whole series of records (a) and enlarged view limited to high silicon contents (b). The horizontal dashed line corresponds to zero recalescence. Symbols in (b) are the same as in (a).

Figure 5 .

 5 Figure 5. Micrographs of sample 16.5 before (a) and after (b) Nital etching.

Figure 6 .

 6 Figure 6. Cooling curves corresponding to all the samples from melts 18 (a) and 22 (b). All cups were single-Te for test 18 while some were double-Te for test 22 as indicated in the caption of (b).

Figure 7 .

 7 Figure 7. Micrographs of sample 18.3 before (a) and after Nital etching (b).

Figure 8 .

 8 Figure 8. Micrographs of SQ sample 22.2 before (a) and after (b) Nital etching.

Figure 4 -

 4 Figure 4-b showed that at high silicon contents, samples SQ 2 and RD 5 had the lowest T e,min

Figure 9 .

 9 Figure 9. (a) Plot of experimental T e,min values assessed in a previous work [1] and measured on the SQ 2 and RD 5 cups during the present work, selecting values with recalescence lower than 5°C. (b) Same plot with superimposed the metastable eutectic temperature calculated with the TCFE-8 database (solid curve), with the horizontal part corresponding to an invariant three-phase eutectic (see text). The dashed curve was obtained by shifting downwards by 8°C the solid curve to account for eutectic growth undercooling in thermal analysis.

  figure 1-b, certainly because of slight modifications in the TCFE database with respect to the

Figure 10 .

 10 Figure 10. (a) plot of the composition of the stable and metastable eutectic lines calculated with TCFE8 with superimposed the composition of the investigated alloys (open circles). (b) Calculated temperatures T EUT , T EW and (solid lines) and experimental T LA temperatures for cup 5 (open circles). The dashed vertical line is positioned at 3.8 wt.% Si.

  . Instead, graphite must have appeared during austenite growth as the carbon content in the liquid gradually enriched toward the metastable eutectic.

  4.21 0.13 0.015 0.007 0.052 0.022 0.034 0.041 0.010 17 3.19 4.28 0.13 0.016 0.007 0.050 0.020 0.032 0.040 0.011 observations reported by Kante and Leineweber. The remainder of the matrix consists of fine three-phase eutectic zones that were too fine to be properly resolved with the SEM used while the field electron gun SEM employed by Kante and Leineweber did.

Figure B2 . 5 Figure

 B25 Figure B2. Low magnification SEM micrograph of the center of sample 19.5

Table 1 .

 1 Chemical composition of the cast alloys (wt.%). ** indicates when double-coated cups were used

	Trial number	C	Si	Mn	P	S	Cr	Ni	Cu	Ti	Sn
	1	3.88 1.04 0.13 0.014 0.008 0.051 0.023 0.037 0.037 0.009
	2	3.86 1.24 0.13 0.014 0.008 0.053 0.022 0.035 0.036 0.009
	3	3.84 1.48 0.13 0.013 0.007 0.053 0.020 0.035 0.036 0.009
	4	3.81 1.71 0.13 0.014 0.007 0.052 0.022 0.036 0.037 0.009
	5	3.73 1.90 0.13 0.013 0.007 0.051 0.020 0.034 0.036 0.009
	6	3.72 2.10 0.13 0.014 0.007 0.049 0.022 0.034 0.037 0.009
	7	3.67 2.31 0.13 0.013 0.008 0.052 0.020 0.034 0.037 0.010
	8	3.63 2.51 0.13 0.014 0.007 0.050 0.022 0.035 0.037 0.010
	9	3.57 2.72 0.13 0.014 0.007 0.051 0.022 0.034 0.038 0.010
	10	3.54 2.91 0.13 0.015 0.007 0.050 0.022 0.033 0.038 0.010
	11	3.52 3.05 0.13 0.014 0.007 0.052 0.020 0.033 0.038 0.010

Acknowledgments

We warmly thank Alexandre Freulon, Cédric Charvillat and Yannick Thébaut from CIRIMAT for their help in the metallographic preparation, X-ray recordings and SEM observations.

Statement of interest

The authors declare that they have no conflict of interest

Appendix A

Table AI. Characteristic temperatures, T LA and T e,min , from all cooling curves and recalescence Rec=(T e,max -T e,min ). All in Celsius. Two digits have been kept for recalescence as this is a relative value. Cups #.2 and #.3 were cubic (SQ) and cups #.4, #.5 and #.6 were cylindric (RD). ** indicates when double-coated cups were used.

Test Cup Reference T LA T e,min Rec

Appendix B

The presence of SC iron silico-carbide was looked for with various means in alloys with high silicon contents. A Bruker D8 Advance diffractometer equipped with a Cu cathode was used in -2 configuration. Records were carried out on various locations of samples 16.5 and 19.5 that all appeared similar. Figure B1 shows the record from the middle of sample 19.5 where ferrite ( Fe ) and cementite (Fe 3 C) were easily identified, leaving one peak at 35.5° that can be associated without much doubt to Fe 8 Si 2 C in agreement with the record 00-026-0798 of the Inorganic Crystal Structure Database (ICSD). The height of this line indicates that the SC fraction was low, consistent with the small amount of this phase reported by Kante and Leineweber [2] for alloys with 3.0 and 4.2 wt.% Si.


Béatrice L'haridon

Béatrice L'

Haridon 羅逸東

AND CLASSICAL LEARNING AS PATH TO SUPREME POWER

Introduction

As a tribute to the unfailing attention Michael Loewe gives to young scholars, I thought it would be the right moment for revisiting a work on Wang Mang I presented at the very start of my academic career. This work, which dates back almost ten years, was warmly supported by Michael, but for various reasons, I was unable to complete it at the time. The original idea was to examine the progress, or even continuity, that characterizes Wang Mang's transformation from minister to emperor. Far from being a sudden and violent coup, Wang Mang's assumption of supreme power was a careful, lengthy, and complex process of increasing his legitimacy first as a man of worth and then as a sovereign, a process that is veiled in some way by the later use of the term "usurpation" to designate this political transformation. This very term, as a judgment regarding the illegitimacy of Wang Mang's actions, tends to divert our attention from the processes of legitimization and the construction of a smooth path from the position of minister to the 2 sovereign, which ultimately allows a replacement by a minister of a sovereign. Whether the date given for the beginning of his ascension is his ennoblement as Marquis of Xindu (Xindu hou 新都侯) in 16 or his nomination as Marshal of State 大司馬 in 8, the process took some two decades. His aim was achieved only with the overthrow of the Han ruling house in 9 C.E. and the founding of a new dynasty, the Xin 新 dynasty, which would last until 23 C.E. 1 The construction of a prestigious genealogy was of particular importance in building the requisite legitimacy Wang needed to ascend to supreme power, a factor already studied in depth by Michael Loewe in his "Wang Mang and his Forbears." 2 That text analyzes how Wang Mang developed his own claim to sovereign legitimacy by establishing a line of ancestors going back to Shun 舜 , and ultimately the Yellow Emperor 黃帝 , and by erecting an unprecedented ensemble of nine shrines for his ancestors. A second way to fashion legitimacy was through the exhibition and the interpretation of bizarre events and fuming 符命 ("mystic commands" or "divine omens"), which according to Wang Mang's biography was characteristic of the last stage on his progress to the throne. 3 1 All dates B.C.E. unless otherwise noted. The reasons for this rapid fall of Wang Mang's regime have been debated by historians, H. Bielenstein and Yü Ying-shih among others, especially regarding the respective roles played by human factors and by natural factors, such as the floods provoked by two changes in the course of the Yellow River. See below note 7. 2 Michael Loewe, "Wang Mang and His Forbears. The Making of the Myth," T'oung Pao 80. 4-5 (1994), 197-222. 3 Han shu 漢書 (Beijing: Zhonghua, 1962), 99A.4093: "This year [8 C.E.] the Marquis of Guangrao, Liu Jing, Battalion Commander to the General of Chariots and Cavalry Hu 3 Here, I would analyze the method employed by Wang Mang to transform his own political identity as a minister through a quite complex web of references to the Classics and to the major figures therein, especially the Duke of Zhou (aka Zhougong 周公). This speaks to the well-known and highly debated topic of Wang Mang's relation to the classicists (Ru 儒), as experts in the Classics, at the end of the Western Han dynasty, and more widely to the relationship between political power and scholarship. 4 During the nineteenth century, this relationship aroused passionate debate among (Shanghai: Graphic Art Book Company, 1947), 173 (mod.). NB: in all citations of earlier works, Wade-Giles has been changed to pinyin, for consistency. 4 For a collective reflection about the role played by one particular Classic, the Zhou li 周 禮, in government conception and organization, in East Asia, see Benjamin A. Elman and Martin Kern, eds., Statecraft and Classical Learning. The Rituals of Zhou in East Asian Society (Leiden: Brill, 2010). Michael Puett's chapter, "Centering the Realm: Wang Mang, the Zhouli, and Early Chinese Statecraft," 129-154, deals with the use of the Zhou li as an effort to centralize the Han. Here I focus more on the rhetorical uses of the Documents classic as it relates to Wang Mang's rise to power. 5 The notion of a radical division between guwen 古文 (an intellectual trend characterized by a strong interest for texts in an older script) and jinwen 今 文 (which roughly designates the officially-sponsored texts written in the current script) has been challenged by several important studies, namely, Hans van Ess, "The Old Text/New Text Controversy: Has the Twentieth Century Got It Wrong?" T'oung Pao 80. 1-3 (1994), to push a new interpretation of the Classics, if not a new classical corpus. His radical accusation that Liu Xin forged false Classics to advance a specific political agenda relied on odd and one-sided conceptions of the political use to be made of the Classics: it neglects the fact that the same authoritative text could be used by supporters as well as opponents, and that the wide range of possible interpretations attached to any Classic was broad enough to obviate the need to "forge" a new Classic.

Here, I inquire into Wang Mang's texts themselves, as interpretations or imitations of classical texts, rather than into his possible endorsement of one or another version of the Classics, partly because Wang Mang's most supportive classicists were not uniform in their vocal support of any one particular Classic or line of thought. As Lu Zhao has written, "Although they are often considered old script/new script opponents, Liu Xin and Shi Dan [師丹] were both Wang Mang's affiliates. The conflict is not so much about partisanship among various intellectual groups as the interplay between innovators and conservatives in the same intellectual community. Liu Xin did not wish to do away with the new script Classics so much as include a broader range of material in their shared corpus." 6 146-70; Michael Nylan, "The chin wen/ku wen (New Text/Old Text) Controversy in Han Times," T'oung Pao, 80.1-3 (1994), 83-145. 6 Lu Zhao, "In Pursuit of the Great Peace: Han Dynasty Classicism and the Making of Early Medieval Classicist Culture," (Ph.D. dissertation, adviser Paul R. Goldin, University of Pennsylvania, 2013). A book based on the dissertation was published in 2019, but I could not consult it.

Studies of Wang Mang generally focus on judgments about this highly debated figure or the reasons for his failure,7 with such approaches addressing his value and success as a sovereign more than his significance as a man who built a path bridging the roles of minister and sovereign. Although the historical figure of Wang Mang has been almost unanimously condemned in Chinese historiography, we will study in detail the ideological preparation for his seizure of power. A short description of this process was given by Gu Jiegang 顧頡剛 in his Qin Han de fangshi yu rusheng 秦漢的方士與儒生. 8 Far from suddenly arrogating the imperial title, Wang Mang built, at every stage of his career, multiple paths to legitimacy so that he appears to have established a continuum between the roles of minister and sovereign. In the process, he masterfully combined ritual elaboration, rhetorical tools, and, more conventionally, physical violence. Pivotal to this process was his emulation of the model presented by Zhougong, which offered a fairly complete plan for creating a continuous path between minister and sovereign.9

Curiously, from Huan Tan 桓譚 (23 B.C.E.-56 C.E.) on, early denunciations of Wang's ideological policy centers on his use of omens while being largely silent on Wang's strong reliance on classical values and continual reference to the Classics. 10 Omens could be used and interpreted by different groups, whereas reference to the Classics clearly implied the responsibility of one specific group (notwithstanding its internal tensions): the classicists or the Ru 儒.

With the restoration of the Han dynasty, it was necessary to radically sever the links between Wang Mang and the classicists. Here also, Huan Tan is significant. Huan Tan was involved in Wang Mang's administration and survived the decade of turmoil during the end of his reign and the founding of Eastern Han. He then wrote various analyses of Wang Mang's failure, thus clearly disavowing any earlier support for Wang.

Later historiography mentions but does not resolve the problem of the many leading 10 In his Xinlun 新論, Huan Tan gives various reasons that contributed to the fall of Wang Mang's dynasty. Among them is his very solitary exercise of power and his fondness for omens. See Timoteus Pokora, Hsin-lun (New Treatise) and Other Writings by Huan T'an (43 B.C.-28 A.D.) (Ann Arbor, MI: Center for Chinese Studies, 1975), 10, 25-27, 30-31, 45-50. Huan Tan does not mention the great support by the classicists during Wang Mang's accession to power, nor does he mention Wang Mang's public emulation of Zhougong. For a contemporaneous accusation, see also the "pamphlet" published by Wei Ao 隗囂 (d. 33 C.E.) and his group during the last rebellion against Wang Mang. This pamphlet, which is referred to in Han shu 99C.4187 and quoted in extenso in the Hou Han shu 後漢書 (Beijing: Zhonghua, 1965), 13.515, focuses on two main accusations, the regicide and the forgery of omens. See Bielenstein, "Restoration," 124: "The former Marquis of Xindu, Wang Mang, has treated rudely and insulted Heaven and Earth, acted contrary to principles, and opposed order. He poisoned and killed Emperor Ping and snatched away his throne. He pretended to have received the mandate of Heaven and forged writings about verifications [of his receipt of the mandate by auspicious omens]. He cheated and misled the masses and aroused to anger the Lord on High. He turned and twisted ornamental expressions in order to fabricate auspicious omens. He made game of the Spirits of Heaven and Earth and praised misfortunes and calamities in song. The bamboos of Ch'u and Yüe are not sufficient to write down his wickedness" (trans. by Bielenstein). Another aspect of Wang Mang's ideological push during his ascent to supreme power is worth considering: its strong reliance on the narratives found in the "Zhou Documents" section of the Documents classic (Shang shu 尚書), and on the political ethics developed therein. This topic contrasts strongly with Wang's use and abuse of omens, which became more prominent in Wang Mang's strategies of legitimization during the last stage before the founding of Wang's "new dynasty," and afterwards, as he consolidated power. Whereas omens were meant to indicate Wang's relation to an anthropomorphic Heaven or cosmic order, the precedents found in the Documents classic were mostly used to elaborate the relationship between the sovereign, ancestors, ministers, and people.

11 Hou Han shu, 28A.956: "When Wang Mang was on the verge between regency and regicide, all the classicists in the empire competed to praise him and offer auspicious omens, in order to attract his favor. Only Huan Tan remained in the background, calm and without speaking. Wang Mang appointed him as an official in charge of music, and when Gengshi took the imperial throne, he was appointed Palace Counsellor." 當王莽居 攝篡弒之際,天下之士,莫不競襃稱德美,作符命以求容媚,譚獨自守,默然無言。 莽時為掌樂大夫,更始立,召拜太中大夫。 12 Han shu, 84.3435: 乃遣大夫桓譚等班行諭告當反位孺子之意. A similar mission of propaganda is mentioned in Han shu, 99A.4987.

The main source of our knowledge about Wang Mang's policy is his lengthy biography in three chapters or juan 卷, which can be compared with the Annals of Emperors Cheng 成帝紀 (Han shu, 10), Ai 哀帝紀 (Han shu, 11), and Ping 平帝紀 (Han shu, 12), the Empress Wang's biography 元后傳 (Han shu, 98), and Zhai Yi's 翟義 biography (Han shu, 84). 13 The degree of distortion in Ban Gu's narrative history, which was written in early Eastern Han under the "restored" Liu-clan, by Ban or his father, has been continually debated. As Hans Bielenstein put it: "Ban Gu's accusations lack substance and therefore do not discredit Wang Mang. They are a historiographical device to misrepresent a man who for political and philosophical reasons had to be branded as incompetent and morally inferior." 14 Although this issue must be kept in mind, it is not central here. The object of my research is official texts and declarations, whose manipulation seems improbable, since they were accessible to all scholars who could consult the imperial archives.

The Foundations for Wang Mang's Seizure of Imperial Power

Before studying the textual elaboration of the transformative path from minister to emperor, it is necessary first to roughly describe the context that made Wang's rise acceptable, especially the intellectual context. Long considered a total betrayal of the Confucian ideal, the ideology developed by Wang Mang has received more balanced 13 On Zhai Yi, see below, note 48. 14 Wang Mang was the greatest practitioner of the Han Confucian scholars' ideals and theories. . . . He succeeded in ending the Former Han without a civil war, through "abdication" rather than military conquest. His success was not achieved by his "hypocritical" and "treacherous" plots, as portrayed in the biography in Han shu, but was based on the ideological and political preparation of generations of Han scholars. 15 As Wang Aihe posits continuities between Wang Mang and earlier classicists, it may be worth examining here a long tradition of biting criticism of Han institutions and policy.

During one memorable debate held before Emperor Jing 景帝, a certain Master Huang 黃 生 expressed, in a transparent metaphor, the idea that the respective positions of the sovereign and the minister were irreversible and absolute: "A cap, even of poor quality, should always be worn on the head, while shoes, no matter how excellent, should stay in their place on the feet." 16 In reality, this unshakable hierarchy could be challenged by the concentration of power in the hands of a member of an imperial or consort clan, but it was also tested, at a deeper level, by Han thought and institutions. Inverting the respective positions of sovereign and subject was an ever-present possibility due to the cyclical conception of dynastic change, which could apply to any dynasty, regardless of its initial success. The main question became when this change would likely happen. Some scholars even proposed a diagnosis of the origin of the rapid decline of the Han dynasty. On this issue, in one of his memoirs to the throne, the great Gongyang scholar Dong Zhongshu 董仲舒 (179-104) wrote,

今漢繼秦之後,如朽木糞牆矣,雖欲善治之,亡可奈何。法出而姦生,令下而詐起, 如以湯止沸,抱薪救火。
Now, Han having inherited from the Qin may be compared with an edifice made of rotten wood and walls of dung: although you have the desire to improve it, there is nothing you can do. Every new law is followed by a new vice; every order issued to those below elicits deception. It is just like pouring burning water to stop boiling or bringing firewood in armfuls to extinguish a fire. 17 predictions about the end of the dynasty. To take one example, following the report of several strange phenomena in 78, Sui Hong 睢弘, who held a position in the imperial administration, took the fatal step of composing a memorial suggesting that the Han dynasty should yield its power to a sage:

漢家堯後,有傳國之運。 漢帝宜誰差天下,求索賢人,禪以帝位,而退自封百里。 如殷周二王後,以承順天命。
As descendant of Lord Yao, the House of Han is doomed to hand over its lands. The Han emperor should therefore look for a worthy man throughout the realm, and abdicate to him the imperial position, and then he should retire to a fief of one square hundred li. In this way, he would comply with Heaven's decree, in the same way as did the descendants of the Yin and Zhou ruling houses. 18 Another prediction expressed by one of the most brilliant classicists of the time, Liu Xiang 劉向 (d. 8) indicated widespread acceptance of this idea that the ruling house's mandate had come to an end. Following a violent earthquake, which happened in Shu commandery in 26, Liu Xiang formulated a prediction regarding the imminent fall of the dynasty, which is recorded in the omenological treatise entitled "Wuxing zhi" 五行志: 19 "The House of Han took its rise from the region of Shu-Han. . . . It is thus certain to fall" 漢家本起於蜀漢. . . . 殆必亡矣. 20 Liu's words do not speak of predestination, because he believes that if the Liu clan pays sufficient attention to Heaven's warnings and reforms its policy accordingly, it could extend the tenure of its mandate. His statement nevertheless contributes to the idea that no dynasty can rest secure in the eternal enjoyment of Heaven's backing; if the omens are not heeded, the House of Han is doomed to fall imminently. 21 At the same time that the idea of the "mortality" of the dynasty once founded by the Liu clan was becoming a widely accepted notion, the power of the Wang clan was dramatically increasing.

Turning to the Wang clan and its position vis-à-vis the Liu clan at court, it appears, from Wang Mang's Han shu biography, that Wang's political position at court was both conventional and exceptional. Several major political crises had erupted due to the power of imperial consort clans, such as the Lü clan after the founder Gaozu's 高祖 death or the Huo 霍 clan after Emperor Wu's 武帝. 22 As a member of Empress Wang's clan, Wang Mang's increasing power in the general context of a succession crisis seems just one more instance of this sort of phenomenon. As Ban Biao described it in the conclusion to the Empress Wang Zhengjun's 王政君 (71 B.C.E.-13 C.E.) biography: 21 On this subject, see also the contributing essays by Liu Tseng-kuei, Shao-yun Yang, and Michael Loewe to Chang'an 26 BCE: An Augustan Age in China, eds. M. Nylan and G. Vankeerberghen (Seattle, WA: University of Washington Press, 2015). 22 Empress Lü 呂雉 (d. 180) took control of imperial power after Gaozu's death and elevated to the rank of king a number of men of her own clan while eliminating kings of the Liu clan and old companions of Gaozu. Huo Guang 霍光 (d. 68) was an important adviser to Emperor Wu who was appointed regent of his young successor, the future Emperor Zhao. Huo managed to have both a daughter and a granddaughter married to emperors, and he exerted control over the imperial succession. After his death, his family, suspected of entertaining imperial ambitions, was destroyed.

漢興,后妃之家呂、霍、上官,幾危國者數矣。及王莽之興,由孝元后歷漢四世為 天下母,饗國六十餘載,群弟世權,更持國柄,五將十侯,卒成新都.
From the founding of the Han dynasty, the imperial consort clans of Lü, Huo, and Shangguan endangered the ruling house repeatedly. It was through the Filial Empress Yuan, who during four reigns remained as Mother of the Empire, enjoying authority over the realm for more than sixty years while her younger brothers in their turns controlled the handles of power, with five of them generals and ten of them marquises, that Wang Mang arose and finally became Marquis of Xindu. 23 For example, Wang Feng 王鳳 (d. 22), the empress' eldest brother, as General-in-Chief (Da Jiangjun 大將軍, from 33 to 22) and concurrently Marshal of State (Da Sima 大司 馬), was largely responsible for imperial policymaking during the reign of Emperor Cheng. 24 Still, Wang Mang's success, both within the powerful Wang clan and more generally at court, was distinctive because he relied on his cultivation of Confucian values, as his filial devotion to his uncle Wang Feng shows. 25 Wang Mang was a highly trained classicist himself. According to the Hou Han shu, Xu Xuan 徐宣 taught him the Changes classic (Yi jing 易經), and Chen Qin 陳欽 the Zuo shi learning 左氏學;26 Wang's biography in the Han shu adds only that he 23 Han shu, 98.4035. Wang Zhengjun survived four emperors: Yuan, her husband, Cheng, her son, Ai, and Ping. 24 The balance of power between Wang Feng and Emperor Cheng was unfavorable for the latter, partly because of Wang Feng's control over omens and over their interpretation. 25 See Han shu, 99A.4039. 14 studied the Ritual classic under the guidance of Chen Can 陳參. 27 Conversant with three of the Five Classics, Wang Mang was probably inspired by the precedents he found therein, which supplied the impressive language Wang needed to hone his own rhetorical tools. As Benoît Vermander has written, "The mastery of discourse, once it is usurped by the sovereign, makes the latter the source of all authority." 28 In Wang Mang's case, the combination of his power base within an imperial consort clan and his "mastery of discourse" (i.e., his ability to wield the rhetoric of the Classics and ritual expectations to his advantage), resulted in an unprecedented and formidable concentration of power in Wang Mang's hands. His early dedication to classical learning, combined with his public professions of reverence for the long-hallowed values of humility and filial piety, allowed him not only to acquire a special place within the Wang clan but also support by many scholars who were fellow classicists or even sworn brothers, as was true in the case of Ban Gu's own grandfather, Ban Zhi 班穉. 29 Later, Wang Mang would claim the right to determine which interpretation of the Classics he would impose by fiat, when opponents 27 Han shu, 99A.4039. 28 "La maîtrise du discours, une fois qu'elle est usurpée par le souverain, fait de ce dernier la source de tout magistère." See Benoît Vermander, "Du rite, de sa production et de ses usages: pratiques et spéculations rituelles en Chine ancienne," Archives de Sciences Sociales des Religions 172 (2015), 147-78. 29 As stated in Ban Gu's autobiography, initially Wang Mang considered Ban Zhi 穉, one of the most brilliant classicists of the time, to be a virtual brother, along with Ban's elder and younger brothers. But later when Ban Zhi failed (or was unwilling) to gather eulogies in praise of Wang Mang among the population of the commandery he governed, Zhi lost Wang Mang's favor and only barely escaped punishment, thanks to an intervention by Empress Dowager Wang. See Han shu, 100A.4204. tried to challenge his rise first to quasi-imperial and then to imperial powers by turning the very same classical references against Wang himself.30

Zhougong 周公: Ritual Precedents and a Scheme for Acquiring Legitimacy Between 1 C.E., when Wang Mang gained complete control over Emperor Ping, and 9

C.E., when he ended his regency and officially ascended to the throne, Wang Mang made repeated references to Zhougong, who constituted a model and precedent allowing a powerful regent to cultivate his reputation for proximity with the figure of the sage ruler.

During this period of a decade, references are also made to Huo Guang 霍光 who occupied the same office of regent during the youth of Han Zhaodi 漢昭帝. Such references do not occur, however, in official pronouncements made after 9 C.E., as thereafter Wang's political discourse focused on Wang Mang's descent from the legendary sage-ruler Shun 舜. To understand the rhetoric of this seminal period of eight years, one must see how the figure of Zhougong, minister and regent, was rediscovered and restyled during late Western Han. In his latter-day persona, as we will see, Zhougong successfully merged the roles of ruler and minister, most likely because he supposedly, after seven years, returned his powers to his liege lord, King Cheng, thereby confirming the stark divide between ruler and minister.

In chapter 8 of the Xunzi 荀子, entitled "The Efficacy of the Classical Learning" (Ru xiao 儒效), the most influential theorist for the Western Han court, sets up Zhougong 16 as his first example of a truly great and effective classicist. Xunzi focuses his description of Zhougong's achievements on the ways he set policy, acting like a sovereign but never seizing the throne. In one extraordinary passage, Xunzi points out the continuities between the status of sovereign and the status of minister:

周公無天下矣。鄉有天下,今無天下,非擅也。成王鄉無天下,今有天下,非奪也。 變勢次序節然也。故以枝代主而非越也;以弟誅兄而非暴也。君臣易位而非不順也。
Zhougong did not possess the realm permanently. The reason he held power in the empire at one point before he relinquished it, is not because he had once usurped the throne. The reason that King Cheng did not hold power in the empire at point, but later came to hold it is not because he seized power from Zhougong. 31 Rather, this change in powerholding was merely the proper sequence in a succession of transformations in accordance with the proper measures. Thus, a branch clan was substituted for the main patriline, yet it was not a transgressive act overstepping proper bounds, and a younger brother Zhougong executed his elder brother, yet this was no act of tyranny. There was a change of places between ruler versus minister and subject, which was nonetheless perfectly comme il faut. 31 Xunzi jijie 荀 子 集 解 (Beijing: Zhonghua, 1988), 115-16. Knoblock's translation proposes a very different reading: "Since he (Zhougong) formerly had the empire and he now no longer held it, his actions did not constitute a 'usurpation.' King Cheng formerly had no empire, whereas now he had an empire; hence the Duke's actions had not constituted a 'seizure of power.'" See John Knoblock, Xunzi: A Translation and Study of the Complete Works (Stanford, CA: Stanford University Press, 1994), vol. 2, 69. I follow Eric Hutton, Xunzi: The Complete Text (Princeton, NJ: Princeton University Press, 2014), p. 53, and the commentator Yang Jing 楊倞 who remarks here: "Shan 擅 means shan 禪. The sentence thus means that Zhougong did not abdicate to King Cheng" 擅與禪同。言 非禪讓與成王也.

Particularly striking is the fact that Xunzi does not raise the question of whether Zhougong seized power, but whether or not the young King Cheng had seized the power that was in Zhougong's hands. Xunzi observes a transition, with no special reverence accorded the hereditary transmission; strictly speaking, his formulation does not accommodate discussions about "usurping" or "seizing" power. His main point in the chapter is that, regardless whether the great classicist is in a position of power, the classicist accomplishes his ethical political mission. 32 This celebrated figure of Zhougong went through a certain eclipse in the political discourse from the Qin dynasty onwards, perhaps because this sort of blurring of the respective roles of sovereign and minister was incompatible with the purpose of consolidating the Han empire. According to Gu Jiegang 顧頡剛, the figure of Zhougong practically disappeared after the founding of the Qin dynasty, only to emerge again, for obvious reasons, during the regencies of Huo Guang and Wang Mang. 33 Yet, as we will see from several passages, Wang Mang relied on the mythical, complex, and debated Let us examine, then, a single incident, the offering of an auspicious white pheasant in 1 C.E., during the reign of the young Emperor Ping under Wang Mang's regency, which many took to be the first "sign" of Heaven's favor for Wang Mang's ascendancy. This offering could not fail to evoke a precedent episode attesting the excellence of Zhougong's regency on behalf of the young King Cheng 周成王, in which a pheasant was also offered. 34 The episode is narrated in an early commentary on the Documents classic, as follows:

交趾之南有越裳國。周公居攝六年,制禮作樂,天下和平。越裳以三象、重九譯而 獻白雉。
To the south of Jiaozhi, there was a country named Yuechang. During the six years of his regency, Zhougong instituted rituals and created musical pieces, and the whole realm was at peace. The people of Yuechang then sent envoys, with multiple translators, to offer a white pheasant as tribute. 35 34 Huo Guang's biography reports that in his final days (in 88 or 87 B.C.E.), Emperor Wu, worried about his young successor's ability to exercise power, encouraged Huo Guang to accept the post of regent, by giving Zhougong's portrait of the earlier sage supporting his young king Cheng. See Han shu, 68.2932. 35 Shang shu dazhuan zhuzi suoyin 尚 書 大 傳 逐 字 索 引 (Hong Kong: Shangwu yinshuguan, 1994), 17 (assigned by editors to the "Jia he" 嘉禾 chapter). This work is usually attributed to Fu Sheng 伏勝 (second century B.C.E.), the first classical master to transmit the Han-era Shang shu, though it bears clear signs of reworking in Eastern Han.. This story of the white pheasant clearly amplifies the idea of Zhougong's preeminence: his wise government, through the institution of music and rites, is recognized through the humble offering made by a distant land's ruler. Thus, the story does not only record an auspicious event but contributes to blur the distinction between minister and sovereign.

The narrative in Wang Mang's biography introduces the similar auspicious event with a sentence that soberly but unambiguously points to political manipulation.

始風 36 益州令塞外蠻夷獻白雉,元始元年正月,莽白太后下詔,以白雉薦宗廟。
Formerly Wang Mang arranged it so that the Yizhou administrator(s) would make the barbarians outside the barriers present a white pheasant as tribute. Then, the first month of the first year of the Yuanshi era, Wang Mang had the empress dowager issue an edict ordering that the white pheasant be offered to the ancestral temple. 37 This manufactured omen led the court scholars to request that Wang Mang be honored following the precedent of Huo Guang (如光故事). There followed Wang Mang's polite refusal (sometimes conveyed by the empress dowager and sometimes coming from Wang Mang directly) that then led to a stronger claim, in a process that would be repeated over and over again during Wang Mang's rise to the throne:

太后問公卿曰。 「誠以大司馬有大功當著之邪? 將以骨肉故欲異之也?」
The Empress Dowager inquired of her chief Counsellors and Ministers, "Is it really because the Marshal of State has rendered such great services that you consider they 36 The same verb feng 風, indicating a manipulation, is used on at least two other occasions with Wang Mang as subject: Han shu, 81.3363; 99A.4049. 37 Han shu, 99.4046. 20 should be made known publicly, or is it because of our blood relation that you wish to distinguish him?" 38 In reply, at this second stage, the Han ministers went beyond the precedent of the Han dynasty to invoke the figure of Zhougong on the basis of the white pheasant. In the final imperial edict awarding Wang with these honors, issued after several refusals by Wang Mang, the offering of the white pheasant is explicitly mentioned.

The offering of the white pheasant, whether invented by Wang Mang or by one of his eager adherents, 40 provided Wang with a valuable opportunity to produce a courtsponsored text that permitted a new step leading to the recognition of Wang Mang as an exceptionally fine minister. The shift to Zhougong, far from being trivial, represents the abandonment of a Han political precedent in favor of a supposedly more ancient one. 41 The Han equilibrium of power is thus challenged by the reference to ancient statutes and titles. This pattern will continue.

The "Nine Conferrals" (jiu xi 九錫) were bestowed on Wang Mang in 5 C.E. This decision, officially announced by the empress dowager herself, responded, supposedly, to the appearance of more than seven hundred auspicious omens, as well as to a memorial detailing in twelve points Wang Mang's political and ritual merits (see below). 42 The definition of these Nine Conferrals varies within the Five Classics corpus, 43 but once again, this form of honorific bestowal had never been practiced prior to Wang Mang's time, except for Zhougong. 44 In the first stage of this process, a long memorial written by 41 Although Huo Guang was considered an exemplary regent who successfully protected the continuity of the dynastic line by governing well as a regent for the young Emperor Zhao (94-74), Huo Guang, was nonetheless a controversial figure, since members of his clan fomented treason and his clan was eliminated only three years after Huo Guang's death. 42 The number twelve is symbolic of a full totality, as the memorial itself (Han shu, 99A.4060) points out: "All these deeds were rarely seen in the past, and even Yu the Great and Hou Ji (Shun's minister) would have found them difficult to accomplish, and yet the Duke [Protector of Han, Wang Mang] has accomplished them in their totality, with an unique and pervasive principle (一以貫之). This is full completion indeed!" 43 See Chauncey S. Goodrich, "The Nine Bestowals During the Han-Wei Period: A Study of a Ritual Donation as a Prelude to Dynastic Change," (Ph.D. dissertation, University of California, Berkeley, 1957). 44 On the contrary, this reward had a great success during the medieval period, when it was frequently used to prepare for a change of regime. On this subject, see François Martin, "Des Faux qui ne trompent personne. Les textes d'abdication sous les Six Dynasties," Extrême-Orient Extrême-Occident 32 (2010), 13-39; Carl Leban, "Managing Heaven's Mandate: Coded Communications in the Accession of Ts'ao P'ei, A.D. 220," in Ancient China: Studies in Early Civilization, eds. David T. Roy and Tsuen-hsuin Tsien (Hong Kong: Chinese University Press, 1978).

Zhang Song 張竦 and submitted to the throne by Chen Chong 陳崇 in 3 C.E. 45 supplied a kind of hagiography recounting twelve memorable deeds of Wang, with comparisons made to the deeds of the ancient sages. Each deed was illustrated by a quotation from a Classic, sometimes supplemented or replaced by a quotation from Confucius' Analects.

The memorial equally recalls how the Han dynasty, from its inception, was able to reward its most important ministers generously. It concludes that Wang Mang, by far the most important of such ministers, should be rewarded as Zhougong was, by offering him the Nine Conferrals and bestowing a fief on his son. The empress dowager discussed the case with the high ministers, but political infighting within Wang Mang's family interrupted the discussion. 46 Two years later, an imperial decree bestowed the Nine Conferrals on Wang Mang.

During the following two years, two revolts challenging Wang Mang's power broke out, the first conducted by Liu Chong 劉崇 in 6 C.E. and the second by Zhai Yi in 7 C.E. 47 The suppression of the first revolt provided the occasion to compose a new 45 Han shu, 99.4053-64. 46 After Wang Mang had banned from court the relatives of the young Emperor Ping, Wang Mang's elder son, Wang Yu 王 宇 , probably concerned about the long-term consequences for their family of such an extreme decision, wanted him to reconsider. He was nevertheless unwilling to remonstrate directly and, knowing his father's faith in auspicious and inauspicious signs, he ordered Lü Kuan 呂寬 to sprinkle his father's doors with blood. The whole plot was discovered, and Wang Yu was forced to commit suicide. 47 Son of Zhai Fangjin 翟方進, an important statesman and classicist, Zhai Yi was the first to accuse Wang Mang of having murdered Emperor Ping. According to his biography in the Han shu, he was well aware that the regency of Wang Mang was only the first step towards the overthrow of the dynasty and said so to his nephew ("He now uses the deeds of Zhougong when he was regent for King Cheng, in order to test reactions in the empire. He will necessarily overthrow the House of Han, we can already see the signs"). See Han shu, 84.3426. eulogy for Wang Mang. The sincerity of the eulogy may be questioned since it was composed by Zhang Song and Liu Jia 劉嘉 (a relative of Liu Chong), who may have been implicated with the leaders and so had to disassociate themselves from the revolt in order to stay alive. The second revolt, far more dangerous than the first, prompted the composition of a long text written in imitation of a chapter in the Documents classic. 48 The memorials and edicts of Wang Mang, when recorded, appear in his own Han shu biography, aside from one crucial exception, "Wang Mang's Declaration" 莽誥, composed and published in 7 C.E., which appears in the biography of his fierce opponent, Zhai Yi. 49 "Wang's Declaration" is modeled on the "Great Declaration" 大誥, the ninth chapter in the "Zhou Documents" section in the Documents classic; tradition held that the "Great Declaration" was composed by Zhougong, when he faced external and intrafamilial opposition during his regency. In Zhai Yi's biography, the text of the declaration is preceded by seemingly anecdotal remarks about the behavior of Wang Mang, who constantly holds the imperial infant in his arms, as if to keep the bodies of the minister and sovereign united, while recalling the precedent of Zhougong:

莽日抱孺子會羣臣而稱曰:「昔成王幼,周公攝政,而管蔡挾祿父以畔,今翟義亦 挾劉信而作亂。自古大聖猶懼此,況臣莽之斗筲!」羣臣皆曰:「不遭此變,不章 聖德。」莽於是依周書作大誥.
48 Zhai Yi's biography gives a description of the turmoil caused by this revolt. The crowd of rebels numbered more than one hundred thousand people, local officers were killed, and fires nearly consumed the imperial palace: Han shu, 84.3437. 49 Han shu, 84.3428-37. This declaration is only referred to in Wang Mang's biography (Han shu, 99A.4087).

Wang Mang, daily embracing the Infant, met with the ministers together and declared, "In the past, when King Cheng was too young to reign and Zhougong acted as a regent, The text of the declaration is quite long and closely follows the declaration attributed to Zhougong in terms of theme and language. One interesting point is the very expression introducing the "Great Declaration" in the Classic, which had already given rise to much debate among the specialists. The king spoke to this effect: A great proclamation we issue unto you, o princes of the many lands, and managers of various affairs. Unfeeling Heaven sends down destruction on Our house, brooking no delay. Greatly, Our young charge, an inexperienced man, has inherited the throne, with its vast territories and heavy responsibilities. He has not yet met with the wise men who would lead the people to peace and security. How much less then may We claim to have attained an understanding of Heaven's decree! 51 50 Han shu, 84.3428. 51 Qu Wanli 屈萬里, Shangshu jinzhu jinyi 尚書今註今譯 (Taibei: Taiwan Shangwu, 1969), 89. James Legge (trans.), The Shoo King or the Book of Historical Documents Did the opening expression wang ruo yue 王若曰 mean that Zhougong spoke as a sovereign or that he spoke in the name of the sovereign? According to Zheng Xuan 鄭玄 (127-200), the term "king" refers to Zhougong, because as a regent he is charged with the most important affairs and so cannot be considered as a minister. Wang Mang somehow managed to exploit this ambiguity when he introduced his own declaration using the new title of She huangdi, "Regent Emperor."

惟居攝二年十月甲子,攝皇帝若曰:大誥道諸侯王三公列侯于汝卿大夫元士御事。 不弔,天降喪于趙、傅、丁、董。洪惟我幼沖孺子,當承繼嗣無疆大歷服事, 予 未遭其明悊能道民於安.
On the day jiazi of the tenth month of the second year of his regency, the Regent Emperor spoke to this effect, "We make a great declaration to the princes, the three dukes, and the lords, and to you, the ministers, counsellors, the members of the administration.

Unfeeling Heaven sends down destruction on the Zhao, Fu, Ding, and Dong clans. It greatly occupies Our thoughts that Our charge, Ruzi, sovery young and inexperienced, has come to inherit this throne, with its vast territories and heavy responsibilities. We have not displayed bright wisdom, nor have We been able to lead the people to tranquility." 52 After the founding of Wang Mang's New dynasty in 9 C.E., at which time he made few references to the precedents contained within the Five Classics, the dramatic progress of the rebellion against Wang Mang's regime gave rise in 23 C.E. to Wang's final attempt to (Taipei: SMC Publishing, 1991), 362, mod. after Nylan and He, forthcoming translation of the Documents classic. 52 Han shu, 84.3429.

the critical, even radical potential of the Classics made these texts double-edged swords, whose obvious manipulation was no less dangerous for the sovereign as for the minister.

For the classicists who wanted more power-sharing utilized the Classics to warn Wang Mang and try to impede his road to supreme power; such classicists feared Wang Mang's concentration of power and the breakdown in political communication, with good reason.

  Chinese intellectuals, following the publication by Kang Youwei of a pamphlet denouncing the "forged Classics," the Xin xue weijing kao 新學偽經考 (Examination of the Classics Forged under the Xin Dynasty). Kang accused one of the most brilliant classicists and supporters of Wang Mang, Liu Xin 劉歆 (d. 23), of forging a set of Classics in order to help Wang Mang seize the throne. 5 Kang Youwei himself was eager Yun, and a subordinate under the Senior Tutor, Zhang Hong, presented memorials reporting more divine omens." See Clyde B. Sargent, Wang Mang: A Translation of the Official Account of His Rise to Power as Given in the History of the Former Han Dynasty

  classicists' interventions promoting Wang Mang's political rise. To defend Huan, the Hou Han shu 後漢書 stresses Huan's lack of support for Wang Mang. 11 Passages in the Han shu, however, clearly show that Huan was a very active supporter, at least at one point during Wang Mang's rise to imperial power: "The Counsellor Huan Tan and others were charged with making known the Declaration (Mang gao 莽誥) [an important piece of Wang Mang's propaganda, see below] and Wang Mang's intention to return the throne to the infant emperor." 12

  These flaws of a legalist empire, which according to Dong Zhongshu could only be exacerbated by Emperor Wu's policies, might have been corrected by giving greater prominence to classical learning at the imperial court during the reigns of Xuan (r. 74-49), Yuan (r. 49-33), and Cheng (r. 33-7), but questions about the legitimacy of the Han continued to be raised by classicists. These questions not only focused on certain legalist policy measures, but also, more fundamentally, on the dynastic mandate's exhaustion and approaching end. Alongside the analysis of Han dynasty weaknesses, court scholars who were hardly marginal figures during the first century B.C.E. provided reflections and 17 Han shu, 26.2504. On Dong Zhongshu, see Gary Arbuckle, "Inevitable Treason: Dong Zhongshu's Theory of Historical Cycles and Early Attempts to Invalidate the Han Mandate." Journal of the American Oriental Society 115.4 (1995): 585-97.

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  figure of Zhougong when he sought to bridge the divide between the roles of minister,

  於是羣臣乃盛陳莽功德致周成白雉之瑞,千載同符。「聖王之法,臣有大功則生有 美號. . . . 莽有定國安漢家之大功,宜賜號曰安漢公,益戶,疇爵邑。」 At this, a crowd of courtiers most forcibly set forth the accomplishments and virtues of Wang Mang that had elicited the auspicious omen in the form of a white pheasant, as in the times of Zhougong and King Cheng, a thousand years earlier. "According to the precepts of the sage kings, if a minister has extraordinary merit, then he should have extraordinary titles of honors during his lifetime. . . . As Wang Mang has the great merit of having settled the dynasty and of having secured peace for the House of Han, the throne should bestow upon him the title of Duke Who Protects the Han. It should increase the number of his households who support him, and should make his titles of nobility and his lands hereditary." 39

  Guanshu and Caishu launched a revolt on behalf of Lufu 祿父 [son of Zhoù 紂, the tyrant whose vile deeds had brought down the preceding dynasty]. Today, Zhai Yi causes disorder on behalf of Liu Xin 劉信 [great-grandson of Emperor Xuan 宣帝]. Since antiquity the great sages were afraid of that, all the more so am I, an insignificant man!" All the ministers replied, "If you had not met this difficulty, your sagely virtue would not be made clear." Then Wang Mang relied on the Zhou Documents to compose his "Great Declaration." 50

  王若曰: 猷,大誥爾多邦,越爾御事。弗弔,天降割于我家,不少延。洪惟我幼 沖人,嗣無疆大歷服。弗造哲,迪民康,矧曰其有能格、知天命!

  Hans Bielenstein, "Pan Ku's Accusations against Wang Mang," in Chinese Ideas about Nature and Society: Studies in Honour of Derk Bodde, eds. C. Le Blanc and S. Blader (Hong Kong: Hong Kong University Press, 1987), 270. assessments in recent studies, notably by Wang Aihe in her Cosmology and Political Culture in Early China. She writes,

See especially the debate between Hans Bielenstein and Yü Ying-shih. According to Bielenstein, the direct cause for Wang Mang's fall was not the failure of his ambitious reforms but a series of natural disasters, particularly the successive floods of the Yellow River. See Hans Bielenstein, "The Restoration of the Han Dynasty, with Prolegomena on the Historiography of the Hou Han shu," Bulletin of the Museum of Far Eastern Antiquities 26.1 (1954), 1-209, esp. 150. According to Yü, Wang Mang's reforms were the main cause for his downfall, since they deprived him of the vital support of the most powerful families (which he seems to equate with the classicists) who had brought him to power. See Yü Ying-shih 余英時, "Dong Han zhengquan zhi jianli yu shizu daxing zhi guanxi" 東漢政權之建立與士族大姓之關係, Xinya xuebao 新亞學報 2 (1965), 216-47.

Gu Jiegang 顧頡剛, Qin Han de fangshi yu rusheng 秦漢的方士與儒生 (Shanghai: Shanghai guji, 2005), 60-65.

The ambiguities inherent in the figure of Zhougong, especially as regards his loyalty to his sovereign, are analyzed by Michael Nylan in her chapter "The Many Dukes of Zhou in Early Sources," in Statecraft, eds.Elman and Kern,

Aihe Wang, Cosmology and Political Culture in Early China (Cambridge: Cambridge University Press, 2000),

 16 Han shu, 88.3612: 冠雖敝必加於首,履雖新必貫於足. In this passage, Master Huang strongly opposes Yuan Gu 袁固, a specialist in the Odes classic who argued that a transfer of the ming 命 (here, the legitimacy to govern) could occur, thus provoking dynastic change. According to Sima Tan 司馬談 and Sima Qian's 司馬遷 biography in the Han shu, a Master Huang (probably the same) taught the "Discourse on the Way" to Sima Tan. See Shi ji 130.3288: 太史公…習道論於黃子。

Han shu, 75.3154. On the ancient notion of abdication in favor of a virtuous minister, see note 32 below.

Han shu, 27B.1457.

After recording this prediction, Ban Gu adds his proof: 其後三世亡嗣,王莽篡位 "After this earthquake, there happened to be three successive emperors who had no heirs, and Wang Mang then assumed the throne."

Hou Han shu, 44.1500; 36.1230: 莽從欽受左氏學,以欽為猒難將軍.

See below the case of Shentu Gang.

Han shu, 99A.4046.

Han shu, 99A.4046.

The report of an auspicious omen could prove to be very beneficial for the administrator who was at the origin of it. One must therefore remain cautious as to the attribution of the forging to Wang Mang himself.

advance on his behalf a persuasive model in the Documents classic. That model was found in the "Metal Coffer" (Jin teng 金縢) chapter, which narrates how Zhougong begged Heaven to spare the life of King Wu, then seriously ill. The troops involved in the 23 C.E. rebellion had taken up the accusation once formulated by Zhai Yi, that Wang Mang had killed Emperor Ping. Repeating Zhougong's gesture, Wang Mang made sure to "reveal" his own supplication to Heaven, likewise kept in a metal box since the fatal illness of Emperor Ping. Plainly, this ultimate act of emulation was meant to demonstrate his innocence proved unconvincing to the rebel troops, who were undeterred and advanced on the capital to unseat him.

Plainly, the Classics were not only used to lend ideological and historical weight to Wang Mang's rise to power, since the Classics were also used to elaborate opposition to Wang's accumulation of power, as we see in Sun Bao's 孫寶 remonstrance in 1 C.E, which also deployed the Documents classic to protest the lack of dissenting voices around Wang Mang. Sun Bao, a noted specialist of the Guliang 穀梁 commentary for the Annals 春秋 classic, was an experienced administrator who frequently faced difficulties and dangers due to his uncompromising character. When Sun vigorously protested the use of portents to claim extraordinary merit for Wang Mang, he was holding the important position of Commissioner of Agriculture (Da Sinong 大司農). 53 When we examine his training and career, nothing distinguished him from the majority of Wang Mang's 53 According to Sun Bao's biography, Wang Mang himself had the Empress Dowager recall him to the high administration after Emperor Ai's death; Han Shu, 77.3262. supporters. But when the appearance of a yellow dragon was reported to the court, Sun Bao was struck by the complacent conformity of the high-ranking ministers:

The Grand Tutor Kong Guang, 54 the Chancellor Ma Gong, 55 and other high officers unanimously praised Wang Mang's virtue as equal to Zhougong's, and saying it should be the object of a formal proclamation in the imperial ancestral temple. Sun Bao said, "Zhougong was the supreme sage and the Duke of Shao a great worthy. Nevertheless, they were not always pleased with one another, as it is abundantly clear from the classic. 56 That does not mean they would harm each other. Lately, the winds and rains are untimely, creating want among the people. Faced with such events, all the ministers speak with one and the same voice, to let [Wang Mang] hear nothing but praise." 57 54 A descendant of Confucius and an important dignitary during the reigns of Emperors Cheng and Ai, Kong Guang gave crucial support to Wang Mang, but after 1 C.E., he seems to have been increasingly distant (Han shu, 81.3362-63). He left the court and died in 5 C.E. His father Kong Ba 孔霸, grandfather Kong Yannian 孔延年, and greatgrandfather Kong Anguo 孔 安 國 , were all eminent specialists of the Documents traditions. Kong Guang became Academician during the reign of Emperor Cheng, due to his deep knowledge of the Classics, as well as of Han institutions. He then became Imperial Counsellor (Yushi dafu), Chancellor (Chengxiang), and from 2 to 1 B.C.E., Grand Tutor (Taishi). 55 Ma Gong, a specialist of the Gongyang commentary to the Annals classic, became Chancellor in 1 B.C.E. and Grand Tutor in 5 C.E. 56 Here, Sun Bao might refer to chapter "Jun shi" 君奭 in the section "Zhou Shu" 周書, which is introduced as a text composed by Zhougong to answer the Duke of Shao's criticism. Both were in charge of assisting King Cheng, according to the Documents traditions: 召公為保,周公為師,相成王為左右,召公不說,周公作君奭. 57 Han shu, 77.3263.

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After this harsh remonstrance, the meeting among the high ministers was interrupted, and Sun Bao was dismissed at the first opportunity. Through this short and efficacious remonstrance, he had used the same weapon as Wang Mang and his supporters, i.e., the Documents classic. Instead of extracting symbolic precedents from the Classic, however, he exposed the underlying spirit of the text, which is undoubtedly polyphonic and preserves different, sometimes even contradictory, views of the ancient sages. According to Michael Nylan, "those trained in the Documents. . . . portrayed even the wisest of sagekings as far from omniscient, making them reliant upon the collective wisdom of numerous supporters and allies." 58 Sun Bao, by referring to the fierce rivalry between two sages as recorded in the Documents, effectively mocked the monolithic support for Wang Mang, which was probably all the more disappointing to many, because Wang Mang had seemed to be willing to rely on a real collective force for actions.

Shentu Gang