西洋哲學從古希臘開始，之所以能「究天人之際」，而哲學家又能「成一家之言」，可以說皆起因於能「通現象之變」。古希臘哲人，在「現象」界生成變化的探究中，從「變」的現象，直透到「常」的本體；因而進入到哲學殿堂的「天人之際」的氛圍。其中，亞里士多德更能在「變」的事實中，奠立「形質說」（Hylomorphism），來詮釋變化的原理，是為「成一家之言」的典範。「形質說」在西洋哲學流變中，亞里士多德（Aristoteles, 384-322 B.C.）開其端，而聖多瑪斯（Thomas Aquinas, 1224/5-1274）極其流。近世以還，不少哲學家費盡心力，以投鞭斷流之勢，設法批判甚至否定傳統的形上學；但對「形質說」卻手下留情。究其原因，並非近世以來的哲人心存忠厚，實因「形質說」本身，立得住腳。 亞里士多德在「天學」（On Heaven），「地學」（On Earth），「物理學」（Physics），「超物理學」（Meta-physics即形上學）等著作中，發揮了其「仰觀俯察」的天份，從「變」的現象，窺探出「變」的原理原則。 關於個別變化的問題，亞氏用「範疇」（Category）中的本質與屬性的劃分：本質不變，屬性在變，來說明現象界的個體變化。關於一般變化（全體變化）的問題，亞氏便用「形質說」來處理。認定每一事物的「從無到有」的開始存在，都是「形式」界定「質料」而形成。到後來，「人」的組成，也是由作為形式的靈魂和質料的肉體結合而成。 「範疇」的課題，聖多瑪斯基本上承傳了亞里士多德的學說，而「形質說」則從哲學轉化到神學的內涵，其中尤其是有關「聖體聖事」（Eucharistia）的課題，以麵酒「質變」（Transsubstantiatio）成耶穌基督的體血；再運用「範疇」的反方面的理解：屬性不變，但本質在變的「奧秘」（Mysterium），作為信仰的內涵。 本論文分二大部分進行：先闡述亞里士多德的「形質說」，後論述聖多瑪斯的「形質說」；前者為溯源，後者為極流。最後，提出作者對「形質說」的一些看法和批判。

　　　　　The reason western philosophy could have touched upon the "relation between Heaven and Man" and become a self-integrated system since ancient Greece is its ability to comprehend the mutability of phenomena. In their exploration of the transformation of phenomena, ancient Greek philosophers could see the substance of constancy embedded in the mutability of phenomena. Among others, Aristotle could build his hylomorphism in the reality of mutability to interpret the principles of transformation, which is the model of self-integrated systems. Regarding the development of western philosophy, hylomorphism was started by Aristotle and reached its climax with Thomas Aquinas. In recent times, many philosophers made enormous efforts to criticize and even reject traditional metaphysics, but not so many efforts in terms of "hylomorphism," for which the reason was the substantiality of hylomophism rather than the kindness of recent philosophers. In his works, On Heaven, On Earth, Physics, and Metaphysics, Aristotle made good use of his ability to observe the universe and recognize the principle of mutability in the phenomenon of mutability. As for particular changes, Aristotle explained individual changes in terms of the distinction between the nature and the attribute of Category-the nature is constant, while the attribute chages. As for general changes, Aristotle dealt with them in terms of hylomorphism. He assumed that the exisistence of everything from non-being to being is formed by defining "Matter" with "Form". In the end, "Man" is composed of soul as the form and matter as the body. On the issue of "Category", Thomas Aquinas basically followed Aristotle's theories, and the philosophical immanence of hylomorphism became theological, expecially exemplified by Eucharistia with the Transsubstantiatio of bread and wine into Christ's blood. Besides, Aquinas made the Mysterium about constant attribute and mutable nature the immanence of faith. This paper is divided into two major parts. First we explain respectively Aristotle's and then Aquinas's hylomorphisms, since the former is the origin and the latter is the climax. In the end, we will present some views and criticisms about hylomorphism.