The Influences of Phenology
on the Order of 24 Solar Terms in Ancient China
XIN Jia-dai, CHEN Yi-wen, QU An-jing（Institute for Advanced Study in History of Science, Northwest University, Xi’an, China）

Abstract

The 24 solar terms is an important part of the traditional Chinese calendar system.

However, when studying the existing historical literature which contains the 24 solar terms, we findthat, as dynasty altered, its name and order changed. Scholars commenced discussing the reasons ofthese changes from the Eastern Han 東漢 dynasty (A.D. 25—220), but it has still not been solved. In
this paper, by analyzing the viewpoints of ancient scholars on this topic, we try to find out the reasons
why they didn’t break through. Based on these reasons, then we discriminate the editions of
Yizhoushu·Shixunjie (逸周書·時訓解) and Huainanzi·Tianwenxun (淮南子·天文訓), the relations of
Waking from hibernation (Qizhe 啓蟄) and Excited insects (Jingzhe 驚蟄), as well as tease out theevolution process of the names and orders of “Rainwater (Yushui 雨水) and Excited Insects”, “Grain
rains (Guyu 榖 雨) and Pure and bright (Qingming 清 明)” recorded in the literature of the 24 solar
terms. From the above we can come to the conclusion that the 24 solar terms has been changed fourtimes in ancient China, and reveal that the order of solar terms is related to phenology, but it is notcompletely determined by the order of corresponding to phenology.
Keywords

the order of 24 solar terms, Waking from hibernation, Excited insects, phenology

When studying the ancient Chinese calendars, we find that the names and orders of 24 solar terms
recorded in the existing calendars were not uniform. Such as, in the Taichu Li (太初暦, 104B.C.) of theWestern Han 西漢 dynasty (202 B.C.—9 A.D.) the records of 24 solar terms is: “立春、驚蟄、雨水、
春分、榖雨、清明……”1 in the early Tang 唐 dynasty (A.D. 618—907), Li Chunfeng 李淳風 recorded
24 solar terms in the Linde Li (麟德暦, 665A.D.) is: “立春、啓蟄、雨水、春分、清明、榖雨……”2 therecords of 24 solar terms in the Shoushi Li (授時暦, 1281A.D.) of the Yuan 元 dynasty (A.D. 1271—
1368) is: “立春、雨水、驚蟄、春分、清明、榖雨……”3
Since these three calendars are all included in the official history of ancient China, they are
reliable. However, we find that the names and orders of 24 solar terms in these three calendars are notexactly the same. Therefore, in this paper we want to solve such several questions as follows: Is this atranscription error? If not, so, which one is the real order of the 24 solar terms? And why did the orderof 24 solar terms change in ancient China?

1

Background

1.1 The records of relevant literature
We divide the relevant literature into non-calendar literature and calendar literature. Non-calendar
literature mainly include the relevant records in Yizhoushu·Shixunjie ( 逸 周 書 · 時 訓 解 ),Huainanzi·Tianwenxun (淮南子·天文訓), Yitongguayan (易通卦驗) and Zhoubisuanjing (周髀算經).
The time span is about from the third century B.C. to the first century A.D. Calendar literature mainly
include the relevant records in these existing calendars from Taichu Li to Shoushi Li. They are mostly
presented in the form of astronomical tables. The time span is from 104 B.C. to 1281 A.D. Then we
1

will introduce them respectively.
In the non-calendar literature, Yizhoushu·Shixunjie was written in about the third century B.C. We
can see that each solar term in the text corresponding to three phenology.4 Huainanzi·Tianwenxun was
written in 139 B.C. The text records the positioning principle of 24 solar terms and mentions that theinterval between each solar term is 15 days.5 In Yitongguayan, the text records the phenology and thelength of the solar shadow corresponding to the 24 solar terms.6 Zhoubisuanjing records the length of
the solar shadow corresponding to the 24 solar terms.7
We sorted out the order of 24 solar terms in the above four non-calendar literature. The changing
parts are shown in Table 1, the order of the other solar terms are the same, so, they are omitted here.
Table 1

The comparison table of 24 solar terms in these non-calendar literature

In addition, we also sorted out the order of 24 solar terms in all the existing calendars. Similarly,
the changing parts are shown in Table 2. It should be noted that after Donghansifen Li (東漢四分暦, 85
A.D.) the order of the 24 solar terms remains unchanged until Daye Li ( 大 業暦 , 597 A.D.), and theorder of the 24 solar terms in the calendars after the Dayan Li (大衍暦, 729 A.D.) has not changed tillnow.
Table 2The comparison table of 24 solar terms in the existing calendars

To sum up, no matter in the non-calendar literature or calendar literature, the inconsistent order of
24 solar terms only on two groups: the first is Excited insects (Jingzhe, 驚蟄) and Rainwater (Yushui,雨水); the second is Grain rains (Guyu, 榖雨) and Pure and bright (Qingming, 清明).

1.2 The views of past dynasties scholars
Firstly, as for the editions of Huainanzi·Tianwenxun and Yizhoushu·Shixunjie, previous scholars
2have been talking differently but no conclusion. In Wulitongkao( 五 禮 通 考 ), Qin Huitian 秦 蕙 田
speculated that these two literature were changed by later generations, but no elaborated.
秦蕙田（1702—1764）《五禮通考》中言：“《時訓》一篇亦後人所託。惟《淮南子》係武帝時書，疑亦後人以時術追改之，非《淮南》之舊也。”8Secondly, as for the relationship between Waking from hibernation (Qizhe, 啓 蟄 ) and Excitedinsects (Jingzhe, 驚蟄), there are two main explanations:
One is that they were regarded as the 24 solar terms at the same time. Du Yu 杜 预 said in
Chunqiushili ( 春秋釋例), in the first month, Beginning of spring (Lichun, 立春) as the nodal solar
terms, Waking from hibernation (Qizhe, 啓蟄) as the medial solar terms. In the second month, Excitedinsects (Jingzhe, 驚蟄) as the nodal solar terms, Spring equinox (Chunfen, 春分) as the medial solar
terms. In the third month, Clear and bright(Qingming, 清明) as the nodal solar terms, Grain rain (Guyu,榖雨) as the medial solar terms.
杜预（222—285）《春秋釋例》中言：“正月節立春，啓蟄為中氣。二月節驚蟄，春分為中氣。三月節清明，榖雨為中氣。”9The other explanation is that in the Han dynasty, to avoid the name of emperor Jingdi 漢景帝,
scholars changed Waking from hibernation to Excited insects. In Kunxuejiwen ( 困 学 纪 闻 ), Wang
Yinglin 王应麟 believed that the reason for changing Waking from hibernation to Excited insects is to
avoid the name of emperor Jingdi of the Han dynasty.
王应麟（1223-1296）在《困学纪闻》中言：“改啓为驚盖避景帝讳”。10
Thirdly, the reasons for the change in the order of Excited insects and Rainwater.
Cai Yong's 蔡邕 opinion is that the order of the solar terms was determined by the corresponding
phenology order.11 However, Chen Xiangdao 陳祥道 didn't agree with Cai Yong's opinion. He believedthat although phenology was related to solar terms, it was not a one-to-one relationship.12 Ji Huang's 嵇璜 opinion is that the order of the solar terms should be better matched with climate.13
Therefore, by analyzing these scholars' views, we can tell why they were unable to completely
solve the problem of the reasons of changing the order of 24 solar terms?
To begin with, they didn't correctly distinguish the editions of Yizhoushu·Shixunjie and
Huainanzi·Tianwenxun.
Next, their explanations of the relationship between Waking from hibernation and Excited insects
are inaccurate.
Finally, they mistakenly thought the order of Excited insects and Rainwater are entirely
determined by the corresponding phenology order and believed that it was caused by a single factor,
such as phenology or climate.

2

The reasons for the change of 24 Solar Terms
Based on these discussions, we analyze the reasons for the change of 24 solar terms from thefollowing three aspects: discrimination of early literature editions; discrimination of the relationshipbetween Waking from hibernation and Excited insects; phenology and solar terms.

2.1

Discrimination of early literature editions
Scholars still have disputes on whether the order of the 24 solar terms in Yizhoushu·Shixunjie

and Huainanzi·Tianwenxun were changed by later generations. Here we will make a judgment bydiscussing whether the content in the text is consistent with the social background at that time.
We know the Huainanzi is a literature in the Western Han dynasty. At that time, the order of the3solar terms is Excited insects first, then Rainwater. But in the existing Huainanzi·Tianwenxun, the orderis Rainwater first, then Excited insects.
Yizhoushu·Shixunjie is the pre-Qin literature. At that time, the solar term Waking from hibernation(Qizhe, 啓蟄) didn’t need to be avoided the name of the emperor Jingdi 漢景帝, and the word Excitedinsects (Jingzhe, 驚 蟄 ) has not yet appeared, but what we see in the existing text is Excited insects(Jingzhe, 驚 蟄 ). Moreover, the records of phenology in Yizhoushu·Shixunjie are also different fromthat of the same period.
Therefore, we believe that the existing editions of these two literature are not original, that's to say,the order of the 24 solar terms has been changed by later generations. Here, we correct the order ofsolar terms in these two literature, as shown in red on Table 3.
Table 3

2.2

The order of solar terms in the original editions of these two literature

Discrimination of the relationship between Qizhe 啓蟄 and Jingzhe 驚蟄In the history of Chinese agriculture, Waking from hibernation (Qizhe, 啓蟄) and Excited insects(Jingzhe, 驚蟄) are special. Waking from hibernation is the only one with dual concepts of phenology
and solar terms, while Excited insects is the solar terms that replaces Waking from hibernation, but its
corresponding phenology and time have changed.
Table 4

The records related to Qizhe in the ancient classical literature

At the beginning, Waking from hibernation (Qizhe, 啓 蟄 ) appeared as a phenology, such as in
Xiaxiaozheng (夏小正), “正月啓蟄”, means the first phenology in the first month.14 By the time of
Zhouli·Kaogongji (周禮·考工記), Waking from hibernation appeared as the medial solar terms in thefirst month.15
4

The above Table 4 collects the records related to Waking from hibernation (Qizhe, 啓蟄) in theancient classical literature. We can see that whether it is a phenology or solar term, it is in the firstmonth, and the corresponding natural phenomenon is that insects begin to wake up from hibernation.
However, insects have not yet crawled out of the ground. Therefore, it is not easy to be observed. Thisphenomenon was confirmed by the literature of Xu Bozheng 许伯政.

清代许伯政（1700—1784）《全史日至源流》中云：“正月啓蟄，雉震呴，《大戴》注
云，‘正月必雷，雷不必聞，惟雉聞之。’盖三陽氣至雷，雖未出地，發聲而已，動于地下，
故土氣震發，蟄蟲爲之昭蘇。”16
Through the study of Liji·Yueling (禮記·月令),17 lvshichunqiu·Shierji (呂氏春秋·十二紀)18 andother literature, we find that the ancients observed activities of insects in detail, and also defined
activities of insects in different periods very clearly. In the early literature on phenology, there are four
phenology involving the activities of insects, as follows: dormant insects begin to stir (蟄虫始振) in
the first month; dormant insects all stir ( 蟄 虫 咸 動 ) in the second month; hibernating insects close
entrances to their burrows (蟄虫坯戶) in the eighth month; and hibernating insects all burrow in (蟄虫咸俯) in the ninth month.
Except for the Yizhoushu·Shixunjie and Huainanzi·Tianwenxun, which were changed by later
generations. At present, Excited insects (Jingzhe, 驚 蟄 ) first appeared in the Taichu Li ( 太 初 暦 ,104B.C.) of Western Han dynasty. At that time, Excited insects as the medial solar terms in the firstmonth, the corresponding phenology should be “dormant insects begin to stir (蟄虫始振)”. We can see,in Shuowenjiezi (說文解字), “啓, 開也; 驚, 馬駭也”, that is, Qi 啓 means begin, start; Jing 驚 means
shock, shake.19 So it seems that Waking from hibernation (Qizhe, 啓蟄) and Excited insects (Jingzhe,驚蟄) have different meanings.
Thus, in Taichu Li, Excited insects as the medial solar terms in the first month, it is not matchedwith the corresponding phenology “dormant insects begin to stir ( 蟄 虫 始 振 )”. Later, in theDonghansifen Li ( 東漢四 分暦, 85 A.D.), Excited insects was moved to the nodal solar terms in thesecond month, which matches the second month phenology “dormant insects all stir (蟄虫咸動)”.
Therefore, Waking from hibernation (Qizhe, 啓蟄) and Excited insects (Jingzhe, 驚蟄) are twosolar terms with different essential meanings in different periods.
2.3

Phenology and Solar Terms
We can divide the period of phenology change into three stages by sorting out the existing relevant

literature.
The first stage, from about the third century B.C. to 139 B.C.
Includes Yizhoushu·Shixunjie《逸周書·時訓解》, Liji·Yueling《禮記·月令》, Lvshichunqiu·Shierji《呂氏春秋·十二紀》and Huainanzi·Shizexun《淮南子·時則訓》. They are the early literature about
recording the phenology corresponding to solar terms, or the phenology corresponding to month.
Among them, Yizhoushu·Shixunjie is the earliest literature to record 24 solar terms and 72 phenology,
that’s to say, each solar term corresponding to three phenology. The other three literature do not refer tothe name of solar term. It records the corresponding phenology of each month, and the number ofphenology recorded each month is not same. There are nine at most, and only four at the least.
The second stage, from 523 A.D. to 665 A.D.
The phenology recorded in the four calendars of Zhengguang Li《正光暦》, Xinghe Li《興和暦》,
Huangji Li《皇極暦》and Linde Li《麟德暦》. Zhengguang Li is the first calendar to introduce phenology
table (523 A.D). We find that once the phenology was introduced into the calendar, it strictly followed
the rules that each solar term corresponds to three phenology. However, compared with the order of5phenology in the first stage, it has the obviously tendency to move backward in this stage. For example:
Duckweed begins to grow “萍始生” and Hoopoe alight on the mulberry trees “戴胜降于桑”, thefirst stage was in the third month, while the second stage was in the fourth month;
Earth-worms curl up “蚯蚓結”, Elaphure sheds antlers “麋角解”, Streams and springs stir “水泉動”, the first stage was in the eleventh month, while the second stage was in the twelfth month and soon.
The third stage, from 729 A.D. to 1281 A.D.
The phenology tables, included in all the existing calendars from the Dayan Li 《 大 衍 暦 》 to
Shoushi Li 《 授 時 暦 》 , are followed the phenological records of the Yizhoushu·Shixunjie, and havecontinued to today.

Figure1 The comparison diagram of phenology order

In this figure above, we can see that the distance of these two curves reflect the degree of movebackward of the phenology order in the second stage. In the first two months, these two curves are very
close, it means that the phenology of the first two months move backward for only one position. Butaround September, these two curves are relatively far away, it means that the phenology of around
September move backward for four positions, that is, nearly 20 days.
In previous studies, according to the phenology order of the second stage tends to move backward,
and in the Great cold (Dahan, 大寒), there is no phenology of the coldest period, “Marshes are thickand solid 水 澤 腹 堅 ”. Therefore, the scholars speculated that the climate during Northern Wei 北 魏
dynasty (A.D. 386—534) has been warm all the time.20
On the basis, we know that the climate changes are not stable in history, and there were still greatchanges in the climate after the Dayan Li ( 大 衍 暦 , 729 A.D.). However, the phenology tables areincluded in the calendar after the Dayan Li, they have not changed. So, our conclusion is that in theearly period when phenology was introduced into the calendar, climate changes would cause thechange in the phenology order, but after the Dayan Li, there is no correlation between climate change
and phenology.
In the calendar, the solar terms were first introduced in the Taichu Li ( 太 初暦 , 104B.C.) of theWestern Han dynasty, while the phenology were first introduced in the Zhengguang Li (正光暦, 523
A.D. ) of the Southern and Northern 南北朝(A.D. 420—589) dynasties. With a time interval of more
6

than 600 years. Since the introduction of phenology into the calendar, the order of the 24 solar terms in
Zhengguang Li, Xinghe Li, Huangji Li and Linde Li was different, but the order of phenology recordedin these four calendars was exactly the same. Similarly, in the Dayan Li and the calendars after it, theorder of 24 solar terms was different from that in Yizhoushu·Shixunjie, but the recorded order ofphenology was exactly the same as that in Yizhoushu·Shixunjie.
Thus, the solar terms and phenology were introduced into the calendar successively. We find thatthe changes of the solar terms and phenology were out of sync. That's to say, the relationship between
them tended to gradually separate from each other.

3

The changing process of 24 Solar Terms in ancient China
Based on the above research results, we summarize the changed part of 24 solar terms in historical

records, as shown in Table 5. Here we can see, the names and orders of the 24 solar terms has beenchanged four times in ancient China.
Table 5The comparison table of 24 solar terms in ancient Chinese literature

The first change is the Huainanzi·Tianwenxun in the Western Han dynasty. This time change onlyshows in the name, the order has not changed. In order to avoid the name of Emperor Jingdi of the Handynasty, Excited insects (Jingzhe, 驚蟄) here replaced Waking from hibernation (Qizhe, 啓蟄) .
The second change is the Donghansifen Li. We can see the order of Excited insects (Jingzhe, 驚蟄)and Rainwater (Yushui, 雨水) were exchanged, and the order of Grain rains (Guyu, 榖雨) and Pureand bright (Qingming, 清明) were also exchanged. Although the records of the 24 Solar Terms in the
Yitongguayan are exactly the same as that in the Donghansifen Li, Yitongguayan as a Wei Shu 緯書, isoften not accepted because its contents are mostly influenced by later generations and the time for
writing is uncertain. Therefore, the time of this change is based on the Donghansifen Li.
As we know from the above discussion, Waking from hibernation has been in the first month,when it was changed as Excited insects. Initially, its order has not changed yet and it's still in the firstmonth. However, the phenology of the first month doesn't match the solar term Excited insects. Excitedinsects was more closely matched with the phenology of the second month “dormant insects all stir (蟄虫咸動)”, so the second change moved it to the second month.
7

The third change are the Daye Li《大業暦》, Huangji Li《皇極暦》, Wuyinyuan Li《戊寅元暦》
and Linde Li 《麟 德暦》during the Sui and Tang dynasties. This time was the chaotic period of thechanges of the 24 solar terms. We can see, in the Daye Li, there are two records of solar terms in
different orders. In addition, we also find that Waking from hibernation (Qizhe, 啓蟄) appeared again
as a solar term in this period, and this may be related to the emperor's concept of governing the country
at that time. This sign of restoring the ancient method is not only reflected in the change of the 24 solar
terms, but also the measurement system in this period also restored the ancient method as standard.
Therefore, in the Sui and Tang dynasties, the ancient method regained the attention by the calendar
makers and it was introduced into the calendar at that time.
However, Zhang Zhouxuan 张胄玄 has not yet formed a unified understanding of how to restore
the ancient method of the 24 solar terms in the Daye Li, so there are two different orders of the solar
terms. When Liu Zhuo 劉焯 refuted the omissions of the Daye Li, he thought that Zhang Zhouxuan’scalendar violated the destiny of heaven in terms of solar terms and it was inconsistent with the celestialphenomena. Therefore, he didn’t adopt the order in Daye Li, but still followed the order in theDonghansifen Li. Until the early Tang dynasty, Wuyinyuan Li and Linde Li gradually reached aconsensus, thus these calendars restored to the same order as the Yizhoushu·Shixunjie.
The fourth change is the Dayan Li of the Tang dynasty, which is changed to the same order as thatin the Donghansifen Li. And Yi Xing 一 行 creatively combined the 72 phenology of the
Yizhoushu·Shixunjie with the 24 solar terms of the Donghansifen Li, which has been used till now.
We find that in the whole changing process of 24 solar terms, Waking from hibernation (Qizhe,啓蟄) in Zhoubisuanjing ( 周髀 算經 ), whether it was considered to restored the old name, or not tohave avoided the name of Emperor Jingdi of the Han dynasty, it was a special case at that time.

4

Conclusions
From the above analysis, our main results consists of four parts:
Firstly, we clarify that the Waking from hibernation (Qizhe, 啓蟄) and Excited insects (Jingzhe,驚蟄) are special solar terms, which are different in terms of their essential meanings and time. Waking
from hibernation is the only solar term with dual concepts of phenology and solar terms. It first
appeared as a phenology, and then evolved into the medial solar terms in the first month. At that time,other solar terms didn’t appear completely. As a result of avoiding the name of emperor Jingdi 漢景帝
of the Han dynasty, Excited insects appeared as a solar term to replace Waking from hibernation.
However, its meaning didn’t match the corresponding phenology, which led to the change of the orderof the 24 solar terms.
Secondly, we can divide the period of phenology change into three stages by sorting out theexisting relevant literature, namely, the first stage (from about the third century B.C. to 139 B.C.),
except for Yizhoushu·Shixunjie, the literature in this stage mainly records the correspondence between
month and phenology, with early features in form and content, which were not completely unified; thesecond stage (from 523 A.D. to 665 A.D.), once the phenology was introduced into the calendar, it
strictly followed the rules that each solar term corresponds to three phenology, and the recorded form
became stable, mature and complete; the third stage (from 729 A.D. to 1281 A.D.), the phenology
tables, included in all the existing calendars from the Dayan Li to Shoushi Li, are followed the records
in the Yizhoushu·Shixunjie, and have continued to today.
Thirdly, the solar terms and phenology were introduced into the calendar successively, and then8participated in some specific calculations. We find that the changes of the solar terms and phenology
were out of sync. That's to say, the relationship between them tended to gradually separate from eachother. The phenology is stable in content and normative in form in the existing calendar. Although it
reflects the climate change in a certain period, the overall performance is stable. After the Dayan Li, thesolar terms and phenology continued in a fixed form.
Fourthly, we find that the names and orders of the 24 solar terms has been changed four times inancient China, namely, the Huainanzi·Tianwenxun (淮南子·天文訓, 139 B.C.) in the Western Han
dynasty; the Donghansifen Li (東漢四分暦, 85 A.D.) in the Eastern Han dynasty; from the Daye Li (大業暦, 597 A.D.) to Linde Li (麟德暦, 665A.D.) during the Sui and Tang dynasties; the Dayan Li (大衍暦, 729 A.D.) in the Tang dynasty.

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