耶穌會士高一志〈譬學•自引〉的論述主軸是一則譬喩中的兩端現象，即一則譬喩中「巳明的所取之端」與「未明的所求之端」間，「如何」能達到合胡越而成肝膽的修辭勸説效果。本文依列日學派在《普通修辭學》中的辭格分類，以語義辭格的分析，解答上述「如何能以彼端代替此端」的修辭設譬問題：按韓霖所題〈譬學•序〉中所謂「理有不可遽達者，必以所知， 喻所未知焉」，以及〈譬學•自引〉中高一志所謂「由顯推隱，以所已曉， 測所未曉」等設譬原則，譬喩中「如何能以彼端代替此端」的修辭問題解讀，應由兩個語彙單位間如何形成表達形式的轉換著手。易言之，「如何能以彼端代替此端」的修辭設譬問題，同時也是語言符號中符表與符旨的形式 與內容問題。在結構語言及符號的層面外，本文最後將辭格的結構討論引導至譬喩在證道上的功能，即高一志「為何」要以彼端代替此端。

This paper presents a thorough scientific analysis of Pixue (The Science of Comparison, 1633), a rhetorical work written by the Italian Jesuit Alfonso Vagnoni 高一志（c. 1568-1640), according to a neo-rhetorical treatise, a General Rhetoric (1981) by Group |i. In the introduction to his late-Ming text Pixue, Vagnoni illustrates ten kinds of comparison in the form of religious aphorisms. As Group |i concisely notes in “Poetics and Rhetoric,” the introduction to A General Rhetoric, that ancient rhetoricians have a mania for naming and these endless nomenclatures have been the evident sign for rhetoric’s decline. Rhetoric, in Group ji’s sense, merits being called a science and falls within the scope of structuralism and semiotics. For this reason they rethink rhetoric in structural terms and formulate a new classification of metaboles: metaplasms, metataxes, metasememes, and metalogisms. By means of structural analyses, this paper deals with the nucleus of a rhetorical comparison, that is, how and why the adduced term (the visible) can be used to clarify the solicited term (the invisible). In the structural linguistic sense, this rhetorical question relates to the alternation of expressions and contents of lexemes, and consequently it must also be taken as a semiotic question.