一般學者多視姚鼐為桐城派古文之集大成者，經本文探究，乃知其早期心力固多專於古文，告歸後講學書院，教授學子之餘，亦多藉詩言志抒懷，漸有所得，以此融貫所聞於海峰之家法，乃得以另開桐城論詩之格局。故知姚鼐所足當「集大成」者，並不止於古文理論彙整之功，更獨到在將古文與詩進行異類文體間之會通。故能一則提發韓愈以詩為文時所賦予「古文」之「言志」精神，一則借鏡古文之章法、結構等觀點於詩體，將桐城論文時所獨具之「義法」精神，進而創發為論詩觀點、詩篇創作、鈔詩評註等會榕詩文之創意，因能啟迪其弟子方東樹建立「以文論詩」之完整論理。

　　　　　Scholars generally feel that Yao Nai epitomized the thinking of the Tungcheng literary school. This paper's investigation will show that although Yao Nai indeed focused most of his attention on kuwen texts during his early period, while teaching after going on leave, he often wrote poetry in his spare time as a means of expressing his feelings and ideas. Yao gradually had some success in his poetry, which was imbued with the style of his teacher Hai Feng, and used it to develop the Tungcheng school's theory of poetry. The eclectic Yao Nai may therefore be credited not only with collecting and organizing kuwen textual theory, but also with deriving a general theory encompassing the different literary forms of poetry and kuwen prose. Yao elucidated and promoted the spirit of "exppressing intentions" that Han Yu bestowed on kuwen prose when he "took poetry as prose," and also applied the composition and structure of kuwen prose to poetry. This application of the Tungcheng's school unique "stylistic approach" to the discussion of prose to the study, writing, and critical annotation of poetry brought about an innovative synthesis of the theory of poetry and prose. This inspired Yao's student Fang Tung-shu to establish a comprehensive theory of "using prose to discuss poetry."