for Love does not gather Strife together and make things out of it,
nor does Strife make anything out of Love, but both act on a third
thing different from both. Some indeed assume more than one such thing
from which they construct the world of nature.

  Other objections to the view that it is not necessary to assume a
third principle as a substratum may be added. (1) We do not find
that the contraries constitute the substance of any thing. But what is
a first principle ought not to be the predicate of any subject. If
it were, there would be a principle of the supposed principle: for the
subject is a principle, and prior presumably to what is predicated
of it. Again (2) we hold that a substance is not contrary to another
substance. How then can substance be derived from what are not
substances? Or how can non-substances be prior to substance?

  If then we accept both the former argument and this one, we must, to
preserve both, assume a third somewhat as the substratum of the
contraries, such as is spoken of by those who describe the All as
one nature-water or fire or what is intermediate between them. What is
intermediate seems preferable; for fire, earth, air, and water are
already involved with pairs of contraries. There is, therefore, much
to be said for those who make the underlying substance different
from these four; of the rest, the next best choice is air, as
presenting sensible differences in a less degree than the others;
and after air, water. All, however, agree in this, that they
differentiate their One by means of the contraries, such as density
and rarity and more and less, which may of course be generalized, as
has already been said into excess and defect. Indeed this doctrine too
(that the One and excess and defect are the principles of things)
would appear to be of old standing, though in different forms; for the
early thinkers made the two the active and the one the passive
principle, whereas some of the more recent maintain the reverse.

  To suppose then that the elements are three in number would seem,
from these and similar considerations, a plausible view, as I said
before. On the other hand, the view that they are more than three in
number would seem to be untenable.

  For the one substratum is sufficient to be acted on; but if we
have four contraries, there will be two contrarieties, and we shall
have to suppose an intermediate nature for each pair separately. If,
on the other hand, the contrarieties, being two, can generate from
each other, the second contrariety will be superfluous. Moreover, it
is impossible that there should be more than one primary
contrariety. For substance is a single genus of being, so that the
principles can differ only as prior and posterior, not in genus; in
a single genus there is always a single contrariety, all the other
contrarieties in it being held to be reducible to one.

  It is clear then that the number of elements is neither one nor more
than two or three; but whether two or three is, as I said, a
question of considerable difficulty.

                                 7

  We will now give our own account, approaching the question first
with reference to becoming in its widest sense: for we shall be
following the natural order of inquiry if we speak first of common
characteristics, and then investigate the characteristics of special
cases.

  We say that one thing comes to be from another thing, and one sort
of thing from another sort of thing, both in the case of simple and of
complex things. I mean the following. We can say (1) 'man becomes
musical', (2) what is 'not-musical becomes musical', or (3), the
'not-musical man becomes a musical man'. Now what becomes in (1) and
(2)-'man' and 'not musical'-I call simple, and what each
becomes-'musical'-simple also. But when (3) we say the 'not-musical
man becomes a musical man', both what becomes and what it becomes
are complex.

  As regards one of these simple 'things that become' we say not
only 'this becomes so-and-so', but also 'from being this, comes to
be so-and-so', as 'from being not-musical comes to be musical'; as
regards the other we do not say this in all cases, as we do not say
(1) 'from being a man he came to be musical' but only 'the man
became musical'.

  When a 'simple' thing is said to become something, in one case (1)
it survives through the process, in the other (2) it does not. For man
remains a man and is such even when he becomes musical, whereas what
is not musical or is unmusical does not continue to exist, either
simply or combined with the subject.

  These distinctions drawn, one can gather from surveying the
various cases of becoming in the way we are describing that, as we
say, there must always be an underlying something, namely that which
becomes, and that this, though always one numerically, in form at
least is not one. (By that I mean that it can be described in
different ways.) For 'to be man' is not the same as 'to be unmusical'.
One part survives, the other does not: what is not an opposite
survives (for 'man' survives), but 'not-musical' or 'unmusical' does
not survive, nor does the compound of the two, namely 'unmusical man'.

  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