胡應麟評杜甫〈登高〉一詩為七律第一。本文試圖從這個角度入手，探討胡對七律的要求，以及評價標準，從而討論杜詩沉鬱頓挫風格的構成要素。胡應麟對〈登高〉的評價非常細緻，不獨將〈登高〉和其他兩首同被譽為七律第一的詩作對比，還和杜甫自己的七律互為優劣，是文本分析的一個經典範例。本文從「順流直下」的標準分析其具體所指，並引證歷代評論者的印象式評語的可能指向，然後再從〈登高〉的結句來分析瘦勁的具體表現，以及為什麼能造成藝術效果。本文希望能夠在古人論詩的基礎之上，用理性的語言分析出美感標準的具體所指，從而肯定某些美感標準對評定詩人風格的意義所在。這是本文的用心。

Hu Ying-lin considers Du Fu's poem, Ascend a Height as the magnum opus of the seven-syllable regulated verse. Using this as a starting point, the current paper investigates Hu's requirement for the seven-syllable regulated verse and assessment standards. It discusses the important elements that construct the contemplative nature（it refers to a contemplative poetic style with a cadence in language use）of Du's poetic style. Hu Ying-ling endows Ascend a Height with a meticulous appraisal. He does not merely compare it with the other two poems which are considered concurrently as magnum opus of the seven-syllable regulated verse. He has also reviewed Du' seven-syllable regulated verse. This is a classic example for the analysis of the current paper. The paper analyses the specificity of the poem based on its coherence which will be used as the evaluation standard. Furthermore, it cites the possible bearing of the impressionistic comments from previous reviewers, and analyses the closing line of Ascend a Height to examine the exact performance of the flexibility of tone of the poem and the reasons that it can create an aesthetic effect. This study emanates from the groundwork of the ancient peoples in poetry and it intends to provide a more concrete analysis on specificity of aesthetic standards that would consecutively affirm the meaning of poets' styles assessment against certain aesthetic standards. This is the aim of the paper.