The agent is the immediate mover; the
subject is the matter; and the object is the form. Thus the process
will go on to infinity if not only the bronze comes to be round, but
also roundness or bronze comes to be; there must, then, be some
We must next observe that every
substance is generated from something which has the same name
("substances" including not only natural but all other products).
Things are generated either by art or by nature or by chance or
spontaneously. Art is a generative principle in something else; nature
is a generative principle in the subject itself1
(for man begets man); the other causes are privations of
are three kinds of substance: (1.) matter, which exists individually
in virtue of being apparent3
(for everything which is characterized
by contact and so not by coalescence is matter and substrate; e.g.
fire, flesh and head;
are all matter, and the last is the matter of a substance in the
strictest sense); (2.) the "nature"4
individually)—i.e. a kind of positive state which is the
terminus of motion; and (3.) the particular combination of these, e.g.
Socrates or Callias. In
some cases the individuality does not exist apart from the composite
substance (e.g., the form of a house does not exist separately, except
as the art of building;nor
are these forms liable to generation and destruction; there is a
distinct sense in which "house" and "health" and every artificial
product, considered in the abstract, do or do not exist5
); if it does so at all, it does so
in the case of natural objects. Hence Plato was not far wrong in
that there are as many Forms as there are kinds
of natural objects; that is if there are Forms distinct from the
things of our world.
Moving causes are causes in the sense
of pre-existent things, but formal causes coexist with their effects.
For it is when the man becomes healthy that health exists, and the
shape of the bronze sphere comes into being simultaneously with the
bronze sphere.Whether any
form remains also afterwards is another question. In some cases there
is nothing to prevent this, e.g. the soul may be of this nature (not
all of it, but the intelligent part; for presumably all of it cannot
be). Clearly then there is no need on these grounds for the Ideas to
exist; for man begets man, the individual begetting the particular
person. And the same is true of the arts, for the art of medicine is
the formula of health.
In one sense the causes and
principles are different for different things; but in another, if one
speaks generally and analogically, they are the same for all. For the
question might be raised whether the principles and elements of
substances and of relations are the same or different; and similarly
with respect to each of the other categories. But it is absurd that
they should be the same for all; for then relations and substance
would have the same constituents.