METAPHYSICS In some places Aristotle identiWes form and quiddity (e.g F 1032a33) and he goes on to say that in the case of humans and other animals, the form and the quiddity are to be identiWed with the soul (F 10 1035b14) This presents a problem: if the soul is the quiddity, and the quiddity is the same as what has the quiddity, does this mean that Socrates is identical with Socrates’ soul? Aristotle seems brieXy ready to contemplate this possibility (F 11 1037a8), but that is not his considered opinion, and he goes on to qualify his identiWcation of soul, form, and quiddity ‘Man and horse and whatever is predicated universally of individuals are not substance Substance is the composite of this deWnition and this matter taken universally’ (F 10 1035b27) That means that having Xesh and blood is indeed part of being human; but having this particular Xesh and blood is not part of being human It is part, however, of being Socrates We may wonder what is the relationship between the pair matter–form and the pair body–soul Aristotle at F 11 1037a5 says that an animal is composed of body and soul, and he clearly identiWes body with matter, but at that point he says not that the soul is form, but that it is Wrst substance He goes on shortly afterwards to say that the primary substance is the form inherent in the thing, and that substance (of another kind) is the composite of this and the matter (F 11 1037a29) To make this cohere with his earlier teaching, we have to assume that he is here calling ‘Wrst substance’ what in the Categories he called ‘second substance’! We are left, however, with a serious problem In studying an earlier passage of the Metaphysics we had good reason to conclude that Aristotle was teaching that in ‘Socrates is human’ the predicate ‘human’ signiWed nothing other than Socrates Now it seems to be suggested that it signiWes Socrates’ form or soul: it is that which provides the deWnition of Socrates, and it is here being distinguished from Socrates’ matter Socrates’ body is clearly part of Socrates: but is it part of Socrates’ deWnition or quiddity? Some light is thrown on this by Aristotle’s treatment of deWnition DeWnitions have parts, and the substances they deWne also have parts: Aristotle takes a chapter to explain that if A is a part of X this does not always mean that the deWnition of A has to be part of the deWnition of X (You don’t have to mention an acute angle in deWning a right angle; just the reverse, in fact; F 11 1035b6.) The deWnition has to mention parts of the 222