The book is a systematic study of the issue of self-individuation in the scholastic debate on principles of individuation (principia individuationis).

The point of departure is a general formulation of the problem of individuation acceptable for all the participants of the scholastic debate: a principle of individuation of x is what makes x individual (in various possible senses of 'making something individual'). The book argues against a prima facie plausible view that everything that is individual is individual by itself and not by anything...