«Materia informata»: Il corpo vivente nella psicologia e nella biologia aristoteliche

The subject of this paper is Aristotle’s notion of the body as the matter of the living being. Beginning with an analysis of the notion of «natural body which has life in potentiality», stated at the beginning of the second book of the De anima (412a 20), it will be shown that it is not possible to identify the matter of the living being apart from its form, i.e. the soul. The conception of the living body as «informed matter» has given rise to a discussion of the impossibility of distinguishing matter (i.e. the living body) and hylomorphic compound (i.e. the living substance) in the context of Aristotle’s psychological theory, a problem which is often referred to as «Ackrill’s problem». It will be shown that Aristotle himself provides precise clues to this distinction in the De anima, already at a lexical level. The criterion for distinguishing the informed matter of the living being from the informed matter that is the living being is to be found in the different degrees of potentiality of the soul/form. This thesis finds fundamental confirmation in the embryological theory formulated in De generatione animalium: by distinguishing different phases of the embryonic development, it will be possible to identify the matter of the living being with the product of conception in the first month of gestation, before being «separated» from the mother. On the basis of these texts, it will therefore be argued that the matter of the living being is essentially informed by the potentiality for life, understood as the connate disposition for the acquisition of a series of soul capacities.