Abstract

Starting from the early treatise "On Being and Essence", I review issues concerning substances composed of matter and form: their hylomorphic composition, individuation, essence as part and as whole, and the analogy between genus/difference and matter/form. Then I discuss substances separated from matter, which may range from human souls and angels (or intelligences) to God. I then turn to Aquinas's later 'Summa Theologica', where he argues that in the end God cannot possibly belong to the category of substance and discuss possible reasons for Aquinas conflicting accounts on this question.