This article will discuss the commentators, commentarial layers, knowledge and argumentation in Kong Yingda’s 孔穎達 (584–648 CE) treatment of the ode ‘Shiyue zhi jiao’ 十月之交 in the Mao Shi zhengyi 毛詩正義 (643 CE). Much had changed between Zheng Xuan 鄭玄 (127–200 CE) and Kong Yingda’s day as concerned the Han (202 BCE–220 CE) world order, the feasibility of its ‘cosmological synthesis’ in the sciences, and man’s understanding of eclipses, such as feature in this ode. Kong’s subcommentary to Zheng’s commentary thus provides a stratigraphic cross section of these changes and an authoritative example of how historical change and scientific progress was to be reconciled with ancient canon. [If space permits,] the article will precede in four sections. The first will discuss the fractures that emerged in both the intellectual ideal – the Han cosmological synthesis – and the social fabric of the astral and mathematical sciences over the period of political disunion from the second to the sixth century CE. Specifically, this section will discuss how lü 律 ‘tono-metrology’, li 曆 ‘mathematical astronomy’, and tianwen 天文 ‘heavenly patterns’ went their own ways, how expert communities were cut off from one another, and how these fractures generated cognitive dissonance in polymathic communities and individuals. Next, after introducing the Mao Shi zhengyi and greater Wujing zhengyi 五經正義 project, we will summarise the contents and arguments of the various commentarial layers and sources cited in Kong Yingda’s expansive treatment of the eclipse at the centre of ‘Shiyue zhi jiao’. In short, Kong expands on Zheng Xuan’s commentary, drawing on a host of other Classical commentators between them, to both support the idea that this eclipse was a bad omen caused by bad governance and that, while there is now evidence that eclipses are in fact meaningless ‘regularities’ (chang 常), it is nonetheless crucial to treat them ‘as if’ for the sake of the ritual and moral order. In Section 3, we will then provide some context to these claims: not only were Zheng Xuan, Kong Yingda and Jia Gongyan students of the greatest figures in the history of astronomy, the majority of the other commentators cited were equally members of a broader polymathic network at the forefront of both Classical studies and the exact sciences. With a clearer idea of the knowledge behind the exegetical layers of the Mao Shi zhengyi, in Section 4 we will then critically assess the arguments presented therein from the vantage of what we know their authors knew so as to understand their strategies to reconcile the irreconcilable. In the case of Zheng Xuan, this involves forcing an alternative explanation for the ‘anomaly’ (yi 異) of this ‘regularity’ based on the date on which it occurred. In the case of Kong Yingda, it involves cherry-picking his sources to muddy the water about the scientific consensus and public, empirical proof of the mathematical predictability of eclipses. Lastly, in the conclusion I will offer some reflections about the conflicting elements of transience and permanence inherent to the very source at the centre of this study: the tragic irony of the fossil of what was once a song buried under layer upon layer of written exegesis that was once meant to be read aloud as a lecture.