are nearer the first mover are prior (e.g. the boy is prior to the man); and the prime mover also is a beginning absolutely. — Others are prior in power; for that which exceeds in power, i.e. the more powerful, is prior; and such is that according to whose will the other — i.e. the posterior — must follow, so that if the prior does not set it in motion the other does not move, and if it sets it in motion it does move; and here will is a beginning.— Others are prior in arrangement; these are the things that are placed at certain intervals in reference to some one definite thing according to rule, e.g. in the chorus the second man is prior to the third, and in the lyre the second-lowest string is prior to the lowest; for in the one case the leader and in the other the middle string is the beginning.
These, then, are called prior in this sense, but (2) in another sense that which is prior for knowledge is treated as absolutely prior; of these, the things that are prior in formula are different from those that are prior in perception. For in formula universals are prior, in perception individuals. And in formula also the accident is prior to the whole, e.g. 'musical' to 'musical man', for the formula cannot exist as a whole without the part; yet musicalness cannot exist unless there is some one who is musical.
(3) The attributes of prior things are called prior, e.g. straightness is prior to smoothness; for one is an attribute of a line as such, and the other of a surface.
Some things then are called prior and posterior in this sense, others (4) in respect of nature and substance, i.e. those which can be without other things, while the others cannot be without them, — a distinction which Plato used.[1] If we consider
the various senses of 'being',[2] firstly the subject is prior (so that substance is prior); secondly, according as potency or actuality is taken into account, different things are prior, for some things are prior in respect of potency, others in respect of actuality, e.g. in potency the half line is prior to the whole line and the part to the whole and the matter to the concrete substance, but in actuality these are posterior; for
