METAPHYSICS from something other than itself, then it must be derived from its own quiddity If the quiddity is suYcient on its own for the acquisition, then it is not a possible but a necessary being If the quiddity is not suYcient, but needs external aid, then that external element is the real cause of the being or not being of the possible being (Metaph 38) Avicenna makes use of this argument to show the existence of a Wrst cause that is necessary of itself, and goes on to list the attributes of this necessary being: it is uncaused, incomparable, unique, and so on But it is important to pause here and reXect on the passage just cited The passage supposes that there can be a subject, one and the same subject, that Wrst possesses non-being and then, at a later stage, possesses being: an X such that Wrst X does not exist and then X exists This is obviously something quite diVerent from an underlying matter that Wrst has one form and then another, as when, in the Aristotelian system, a piece of clay takes diVerent forms or one element is transmuted into another (cf Metaph 73) But exactly what kind of metaphysical entity we are being oVered is unclear Is the subject that passes from non-being to being (and vice versa) the universe, or a species, or an individual? When we read this passage, does Avicenna want us to have in mind ‘Once the universe did not exist’ or ‘There used to be dinosaurs, but now there aren’t’ or ‘First there wasn’t Socrates, but then there was’? Each of these thoughts raises metaphysical problems, but let us concentrate on the last of the three, which is both the clearest and the most problematic Surely, before Socrates existed, there was no such subject to have predicates attached to it, or, if you like, there was no Socrates around to be doing the non-existing It seems diYcult to talk about non-existent individuals, because of the impossibility of individuating what does not exist Well, how we individuate what does exist? Aristotle believed that one individual of a particular species was distinct from another because it was a diVerent parcel of matter But what does not exist is not a part of the material universe and hence cannot be individuated by matter But need Avicenna accept that matter is the sole individuating feature? To answer this, we need to look at what Avicenna tells us about the relationship between universals and particulars A concept can be universal, he says, in diVerent ways It can be something that is, in actual fact, truly predicated of many things, such as human It may be something that it is logically possible to predicate of many things, but which in fact is not 191