勇德以比較接近理性官能的「憤情」(the irascible)為主體，在四樞德中排名第三。多瑪斯對勇敢/勇德的討論，包括「自身」(In Itself)與「勇德的組成部分」(Its Parts)二方面；在「勇德的組成部分」方面，又從「普遍地」(In General)、「個別地」(In Particular)、「勇德的神恩/禮物」(The Gift of Fortitude)和「勇德的訓誡」(Its Effects-The Precepts of Fortitude)等四點闡明。文本以多瑪斯最重要的代表作《神學大全》第二部的第二部分(Secunda Secundae)的第一百二十三間到第一百四十問為主。由於篇幅之故，本文只談第一方面的「勇德自身」。首先，析論出「Fortitudo(fortitude)」的確為一德行，一特殊德行，稱為「勇德」，關涉死亡之危險；其次，指出勇德的主要行為在於「殉道」(martyrdom)；再候，較比地呈顯出三種相反勇德之惡；「恐懼」(fear)、「無懼」(fearlessness)與「大膽」(daring)；最後，結論出勇德的意義與價值在於；一方面確立了四樞德之一、名列第三之特殊德行的特殊意涵，即「關涉死亡危險之恐懼，使人能夠克勝恐懼，視死如歸，冒險犯難，甘受迫害」；另一方面則又提供「穩定性」的特點作所有倫理德行所共有之性質，「確保人在困境中有毅力，在追求善時有恆心」。

　　　　　"Fortitude" focuses on "the irascible," which is closer to rational sense, and ranks as the third one in the four cardinal virtues. Aquinas's discussion includes "fortitude in itself" and "fortitude in parts," is explicated in terms of "fortitude in general", "fortitude in particular", "the gift of fortitude", and "the precepts of fortitude." The main part of this paper composes of Questions 123~140 in Secunda Secundae of Aquinas's most important work Summa Theologica. In view of this limits in volume, this paper focuses on "fortitude in itself." First, we make an analysis that fortitude (fortitude) is certainly a special virtue involving the danger of death; second, we point out that the major act of fortitude is martyrdom; furthermore, we compare there evils as opposed to fortitude: fear, fearlessness, and daring. Finally, we conclude that the implications and values of fortitude are: on the one hand, they affirm the special implications of fortitude as one of the four cardinal virtues and the third special virtue, which are the fear involving the danger of death enables one to overcome fear, face death calmly, take risks, and endure persecution; one the other had, "stability" is offered as the common feature of all ethical virtues, "assuring that one is persistent in hardship can consistent in the pursuit of good. "