 The same ideas concerning forma partis and forma totius are restated in the first part of the later Tractatus de formis, where Burley continously identifies the human form with the intellective soul (pp. 9, 10, and 15). In this work, he deals with the nature and ontological status of prime matter and the distinction between substantial and accidental forms. The thesis of the real distinction between the essence and its individuals is not yet supported, and Averroes’s influence is still heavy. Burley defines substantial forms as those forms which immediately perfect matter and give existence (esse simpliciter) to the composite, whereas accidental forms presuppose the existence of the composite, and perfect it. As a result, individuals belonging to the same natural species differ from each other because of their own matter, substantial form (or essence), and accidental forms (p. 9).