本文由「多瑪斯廿四論題」中第廿一條論點與《神學大全》(Summa Theolgica)卷二第一部皆有關意志的題節，相互印證闡述，以釐清人性行為(actus humamus)中的意志與理智概念。在第廿一條的論題中，主要指出理智先於且高於意志的事實，對於意志本質的表現，如何在理智判斷的推動下做選擇，並點出人性行為如何顯示人的判斷和人格及責任性的問題。就廿一條我們可了解多瑪斯以「存有」作為基礎的形上思想，在討論意志問題時與同樣來自靈魂的理智能力相依屬，並建構在「人」這「有限有」(contingency being)的生成和變化上。 因此人的道德性和行為的適切性，簡單的說就是與人的「能力」和這個能力的來源和基礎的符應

　　　　　In this article, the twenty-first thesis of “Aquinas's twenty-four theses” and the first part in Volume II of summa Thelogica are applied to prove and explicate each other so as to clarify the concepts of will and intellect that are found in actus humamus. The twenty-first thesis primarily notes that fact that intellect is prior and superior to will, shows how to express the nature of will according to the judgment of intellect, and points out how actus humamus manifests the issues about man's judgment, personality, and sense of responsibility. From the twenty-first thesis, we can understand that Aquinas bases his metaphysical thoughts on being, discusses the issue of will as related to the spiritual capacity--intellect, and founds it on the generation and transformation of the “contingency being” of “man.” Therefore, the appropriateness of man's morality and acts are, to put it simply, the correspondence between man's “capacity” and its origin and foundation.