Physics   

We speak of 'becoming that from this' instead of 'this becoming that'
more in the case of what does not survive the change-'becoming musical
from unmusical', not 'from man'-but there are exceptions, as we
sometimes use the latter form of expression even of what survives; we
speak of 'a statue coming to be from bronze', not of the 'bronze
becoming a statue'. The change, however, from an opposite which does
not survive is described indifferently in both ways, 'becoming that
from this' or 'this becoming that'. We say both that 'the unmusical
becomes musical', and that 'from unmusical he becomes musical'. And so
both forms are used of the complex, 'becoming a musical man from an
unmusical man', and unmusical man becoming a musical man'.
But there are different senses of 'coming to be'. In some cases we do
not use the expression 'come to be', but 'come to be so-and-so'. Only
substances are said to 'come to be' in the unqualified sense.
Now in all cases other than substance it is plain that there must be
some subject, namely, that which becomes. For we know that when a
thing comes to be of such a quantity or quality or in such a relation,
time, or place, a subject is always presupposed, since substance alone
is not predicated of another subject, but everything else of
substance.
But that substances too, and anything else that can be said 'to be'
without qualification, come to be from some substratum, will appear on
examination. For we find in every case something that underlies from
which proceeds that which comes to be; for instance, animals and
plants from seed.
Generally things which come to be, come to be in different ways: (1)
by change of shape, as a statue; (2) by addition, as things which
grow; (3) by taking away, as the Hermes from the stone; (4) by putting
together, as a house; (5) by alteration, as things which 'turn' in
respect of their material substance.
It is plain that these are all cases of coming to be from a
substratum.
Thus, clearly, from what has been said, whatever comes to be is always
complex. There is, on the one hand, (a) something which comes into
existence, and again (b) something which becomes that-the latter (b)
in two senses, either the subject or the opposite. By the 'opposite' I
mean the 'unmusical', by the 'subject' 'man', and similarly I call the
absence of shape or form or order the 'opposite', and the bronze or
stone or gold the 'subject'.
Plainly then, if there are conditions and principles which constitute
natural objects and from which they primarily are or have come to
be-have come to be, I mean, what each is said to be in its essential
nature, not what each is in respect of a concomitant
attribute-plainly, I say, everything comes to be from both subject and
form. For 'musical man' is composed (in a way) of 'man' and 'musical':
you can analyse it into the definitions of its elements. It is clear
then that what comes to be will come to be from these elements.
Now the subject is one numerically, though it is two in form. (For it
is the man, the gold-the 'matter' generally-that is counted, for it is
more of the nature of a 'this', and what comes to be does not come
from it in virtue of a concomitant attribute; the privation, on the
other hand, and the contrary are incidental in the process.) And the
positive form is one-the order, the acquired art of music, or any
similar predicate.
There is a sense, therefore, in which we must declare the principles
to be two, and a sense in which they are three; a sense in which the
contraries are the principles-say for example the musical and the
unmusical, the hot and the cold, the tuned and the untuned-and a sense
in which they are not, since it is impossible for the contraries to be
acted on by each other. But this difficulty also is solved by the fact
that the substratum is different from the contraries, for it is itself
not a contrary. The principles therefore are, in a way, not more in
number than the contraries, but as it were two, nor yet precisely two,
since there is a difference of essential nature, but three. For 'to be