mathematics, and starting, we might perhaps say, with the doctrines of Newton’s ‘Principia,’ anything which lies beyond these doctrines being taken for granted. But in Aristotle’s Natural Philosophy nothing is taken for granted. He commences by inquiring into the nature of “Existence;” and sets himself to answer some of the puzzles with which his predecessors, the philosophers of Greece, had racked their own and other people’s brains. They had said, “How is it possible for anything to come into existence? Out of what can it come? It must come either out of the existent or the non-existent. But it cannot come out of the existent, else it would have existed already; nor can it come out of the non-existent, for out of nothing nothing can come.” Aristotle solves this dilemma (‘Phys.’ I. viii.) by introducing what now seems a simple enough distinction—that between the “possible” and the “actual;” things come into existence, that is, into actuality, out of the state of the possible. Now the possible, or potential, is in one sense non-existent, as it is nothing actual; but, on the other hand, it is not mere nonentity, as it is by hypothesis a possibility of existence. All this may appear to be a mere matter of words; and it may be asked what we gain by having the words “possibility” and “actuality” added to our, vocabulary? But, in fact, men think by means of words; and if a new formula can clear up the notions connected with such often-occurring terms as “is” or “became,” it is a gain, the reality of which is shown by the perplexities to which thinkers had been reduced to for the want of it.
