perhaps both the latter are the same.) We must, however, state the
most proximate causes. What is the matter? Not fire or earth, but the
matter proper to man.
Thus as regards generable natural
substances we must proceed in this manner, if we are to proceed
correctly; that is, if the causes are these and of this number, and it
is necessary to know the causes. But in the case of substances which
though natural are eternal the principle is different. For presumably
some of them have no matter; or no matter of this kind, but only such
as is spatially mobile.1
Moreover, things which exist by
nature but are not substances have no matter; their substrate is their
substance. E.g., what is the cause of an eclipse; what is its matter?
It has none; it is the moon which is affected. What is the moving
cause which destroys the light? The earth. There is probably no final
cause. The formal cause is the formula; but this is obscure unless it
includes the efficient cause.E.g., what is an eclipse? A privation of
light; and if we add "caused by the earth's intervention," this is the
definition which includes the <efficient> cause. In the
case of sleep it is not clear what it is that is proximately affected.
Is it the animal? Yes; but in respect of what, and of what
proximately? The heart, or some other part. Again, by what is it
affected? Again, what is the affection which affects that part, and
not the whole animal? A particular kind of immobility?
Yes; but in virtue of what
affection of the proximate subject is it this?
some things both are and are not, without being liable to generation
if they exist at all; and in
general the forms and shapes of things (because white does not come to
be, but the wood becomes white, since everything which comes into
being comes from something and becomes something)—not all
can be generated from each other.
White is not generated from black in the same way as a white man is
generated from a black man; nor does everything contain matter, but
only such things as admit of generation and transformation into each
things as, without undergoing a process of change, both are and are
not, have no matter.
There is a
difficulty in the question how the matter of the individual is related
to the contraries. E.g., if the body is potentially healthy, and the
contrary of health is disease, is the body potentially both healthy
and diseased? And is water potentially wine and vinegar? Probably in
the one case it is the matter in respect of the positive state and
form, and in the other case in respect of privation and degeneration
which is contrary to its proper nature.
There is also a
difficulty as to why wine is not the matter of vinegar, nor
potentially vinegar (though vinegar comes from it), and why the living
man is not potentially dead. In point of fact they are not; their
degeneration is accidental,