一、美之存有學的確立：從形上學的觀點，指出存有的超越屬性包含一、真、善、美。美至少可以間接地被視為存有的超越屬性之一。二、多瑪斯關於美之存有學的線索：多瑪斯對於美的條件指出有三個：整一（integrity）或完備（perfection），恰當的比例（proportion）或和諧（harmony）；以及明亮（brightness）或清晰（clarity）。多瑪斯除了指出美的觀念的三個條件之外，他也指出美和理性的關係，特別是美和形式的關係。多瑪斯首先指出美、善的共同基礎在於形式。多瑪斯也特別強調視覺與聽覺。多瑪斯的美學發展的路線是先從感性的愉悅作為出發點，然後再提昇到理性判斷的美學。這一思想的路線和他的形上學思想的進路是完全一致的，在實體的探究過程中，多瑪斯也是先從經驗之知展開，然後提昇到理性知識的階段。為多瑪斯而言，美的體驗是一種超越知識與感覺的特殊狀態，這種超越的狀態被稱之為「忘我」（ecstasy）。在這種忘我的狀態中也融合了「愛」。三、馬里旦的進一步詮釋與發展：馬里旦在詮釋美的特性時，他特別 強調理性所扮演的角色。他把「美」當成是理性的愉悅。此外，由於「光輝」是多瑪斯的美之三特性中最有特色的一點，因此馬里旦在對於這一點的詮釋上著墨又更多。馬里旦定義「美」為「安排質料的各部份比例的形式的光輝」，或是「被合理地安排的質料之上的理性的光芒」。馬里旦在詮釋多瑪斯美學思想的時候，並不墨守成規而是能夠活用在真實的藝術鑑賞活動當中。四、馬里旦的「美之存有學」的意義：第一，補足士林哲學在美學研究上的缺乏。第二，強調美在本質上和理性的密切相關，才又使美學的研究找到返回理性中心的路線。第三，是哲學史上少數能夠充分了解藝術活動的真面貌，然後再來談美學理論的哲學家。

　　　　　The article is divided into four sections, ie., Section I : Establishment of Ontology of Beauty Section II : A clue to Ontology of Beauty according to Thomas Aquinas Section III: Further interpretation and development of Ontology of Beauty by Jacques Maritain Section IV: An evaluation of Maritain's Ontology of Beauty Form the perspective of metaphysics, Jacques Maritain proposes that the Beautiful can be regarded, at least indirectly, as a Transcendental Attribute on the par of the One, the True, and the Good. According to Thomas, the requirements for the Beautiful are three fold, they are integrity or perfection, due proportion or harmony, and brightness or clarity. In addition, Thomas points out the relationship between Beauty and reason, especially the relationship between Beauty and form. In the opinion of Thomas, both Beauty and Good are based on form. Besides, Thomas emphasizes sight and audition. His approach to aesthetics starts from sensible pleasures, then reaches to rational judgments. This line of thinking coincides with his approach to metaphysics. While investigating substance, Thomas begins with empirical knowledge which is followed by rational knowledge. To Thomas, aesthetic experience lies in a special union named ecstasy, which is beyond both knowledge and sensation. Love is also implicated in the state of ecstasy. In interpreting the characteristics of the Beautiful, Maritain lays special emphasis on the role played by reason. He looks upon “the Beautiful” as rational pleasures. What is more, “brilliance” is the most remarkable among the three characteristics of the Beautiful mentioned by Thomas, therefore Maritain says much more on this. Beauty as is defined by Maritain is “the splendor of the form on the proportional parts of matter”, or “a flashing of intelligence on a matter intelligibly arranged”. In interpreting the aesthetics of Thomas, Maritain does not abide by tradition rather he transforms it into a creative thought which accords with real appreciation of artistic activities. As far as an evaluation of Maritain's Ontology of Beauty is concerned, first, it supplies the lack of aesthetic theory on the part of scholasticism. Second, due to the emphasis it lays on the close relation between Beauty and reason when viewed from the essence of the former, it prompts aesthetic researches back to the line of thinking which centers on reason. Third, Maritain counts as one of few philosophers in history who do aesthetic researches after a true and full understanding of artistic activities.