12. Plato[66] agreed with this, and being persuaded that, by
participation, matter does not receive form and shape, as would some
substrate that should constitute a composite of things intimately
united by their transformation, their mixture, and their common
affections; in order to demonstrate the opposite, namely, that matter
remains impassible while receiving forms, invented a most apposite
illustration of a participation that operates without anything being
affected (namely, that engravers, before using dies on the soft wax,
clean them carefully). Almost any other kind of illustration would
fail to explain how the substrate can remain the same in the presence
of forms. While trying to achieve his purpose, Plato has raised
many questions; he has besides applied himself to demonstrate that
sense-objects are devoid of reality, and that a large part of their
hypostatic substance is constituted by appearance. Plato demonstrates
the permanence and identity of matter by showing that it is by the
figures with which it is endued that matter affects animated bodies,
without itself suffering any of their affections. He wishes to convince
us that in being endued with these figures, matter undergoes neither
affection nor alteration. Indeed, in the bodies that successively
assume different figures, we may, relying on analogy, call the change
of figures an alteration; but since matter has neither figure nor
existence,[67] how could we, even by analogy, call the presence of a
figure an alteration? The only sure way of avoiding a misunderstanding
in expression is to say that the substrate possesses nothing in the
manner it is usually supposed to possess it. How then could it possess
the things it contains, unless as a figure? Plato's illustration means
that matter is impassible, and that it contains the apparent presence
of images which are not really present therein.
PLATO'S FIGURATIVE LANGUAGE MIGHT LEAD TO ERRORS ABOUT HIS REAL
OPINIONS.
We must still further preliminarily insist on the impassibility of
matter; for by using the usual terms we might be misled into wrongly
thinking that matter could be affected. Thus Plato speaks[68] of matter
being set on fire, being wetted, and so forth, as if it received
the shapes of air or water. However, Plato modifies the statement
that "matter receives the shapes of air and water" by the statement
that matter "is set on fire and wetted," and he demonstrates that by
receiving these shapes it nevertheless has none of its own, and that
forms do not more than enter into it. This expression "matter is set on
fire" must not be taken literally; it means only that matter becomes
fire. Now to become fire is not the same thing as being set on fire; to
be set on fire can achieve no more than what is different from fire,
than what can be affected; for that which itself is a part of fire
could not be set on fire. To insist on the opposite would amount to
saying that metal itself formed a statue, or that fire itself spread
into matter and set it on fire. The theory that a ("seminal) reason"
had approached matter, forces us to question how this reason could have
set matter on fire. The theory that a figure had approached matter
would imply that that which is set on fire is already composed of
two things (matter and a figure), and that these two entities form a
single one. Although these two things would form a single one, they
would not affect each other, and would act only on other entities. Nor
would they even in this case act jointly; for one would effect no more
than to hinder the other from avoiding (form). The theory that when
the body is divided matter also must be divided, would have to answer
the question, How could matter on being divided, escape the affection
undergone by the composite (of form and matter)? On such a theory, one
might even assert that matter was destroyed, and ask, Since the body is
destroyed, why should not matter also be destroyed? What is affected
and divided must be a quantity or magnitude. What is not a magnitude
cannot experience the same modifications as a body. Therefore those who
consider matter affectible would be forced to call it a body.