8. (According to Aristotle[59]), it is absolutely necessary that what
can be affected must have powers and qualities opposed to the things
that approach it, and affect it. Thus, it is the cold that alters the
heat of an object, and humidity that alters its dryness, and we say
that the substrate is altered, when it ceases being hot, and grows
cold; and ceasing to be dry, becomes humid. Another proof of this truth
is the destruction of the fire that, by changing, becomes another
element. Then we say that it is the fire, but not the matter that has
been destroyed. What is affected is therefore that which is destroyed;
for it is always a passive modification that occasions destruction.
Consequently being destroyed and being affected are inseparable
notions. Now it is impossible for matter to be destroyed; for how
could it be destroyed, and in what would it change?
OBJECTION THAT MATTER MUST BE PASSIBLE IF ITS QUALITIES CHANGE AS THEY
DO.
It may be objected that matter receives heat, cold, and numerous, or
even innumerable qualities; it is characterized by them, it possesses
them as somehow inherent in its nature, and mingled with each other, as
they do not exist in isolated condition. How could nature avoid being
affected along with them,[60] serving as it does as a medium for the
mutual action of these qualities by their mixture?[61] If matter is
to be considered impassible, we shall have to consider it as somehow
outside of these qualities. But every quality which is present in a
subject cannot be present in it without communicating to it something
of itself.
DIFFERENT SENSES OF "PARTICIPATION" WILL ALLOW FOR MATTER TO REMAIN
IMPASSIBLE.
9. It must be noticed that the expressions: "such a thing is present to
such a thing" and "such a thing is in such other thing" have several
meanings. Sometimes one thing improves or deteriorates some other
thing by its presence, making it undergo a change; as may be seen in
bodies, especially those of living beings. Again, one thing improves
or deteriorates another without affecting it; this occurs with the
soul, as we have already seen.[62] Again, it is as when one impresses
a figure on a piece of wax; the presence of the figure adds nothing to
the (nature) of the wax, and its destruction makes it lose nothing.
Likewise, light does not change the figure of the object which it
enlightens with its rays. A cooled stone participates a little in
the nature characteristic of the thing that cools it; but none the
less remains stone. What suffering can light inflict on a line or
a surface?[63] One might perhaps say that in this case corporeal
substance is affected; but how can it suffer (or be affected) by the
action of light? Suffering, in fact, is not to enjoy the presence
of something, nor to receive something. Mirrors, and, in general,
transparent things, do not suffer (or are not affected) by the effect
of images that form in them, and they offer a striking example of the
truth we are here presenting. Indeed, qualities inhere in matter like
simple images, and matter itself is more impassible than a mirror.
Heat and cold occur in it without warming or cooling it; for heating
and cooling consist in that one quality of the substrate gives place
to another. In passing, we might notice that it would not be without
interest to examine whether cold is not merely absence of heat. On
entering into matter, qualities mostly react on each other only when
they are opposite. What action, indeed, could be exercised by a smell
on a sweet taste? By a color on a figure? How, in general, could things
that belong to one genus act on another? This shows how one quality can
give place to another in a same subject, or how one thing can be in
another, without its presence causing any modification in the subject
for which or in which it is present. Just as a thing is not altered
by the first comer, likewise that which is affected and which changes
does not receive a passive modification, or change, from any kind of an
object. Qualities are affected only by the action of contraries. Things
which are simply different cause no change in each other. Those which
have no contraries could evidently not be modified by the action of any
contrary. That which is affected, therefore, can not be matter; it must
be a composite (of form and matter), or something multiple. But that
which is isolated or separated from the rest, what is quite simple must
remain impassible in respect of all things, and remain as a kind of
medium in which other things may act on each other. Likewise, within
a house, several objects can shock each other without the house itself
or the air within it being affected. It is therefore qualities gathered
in matter that act on each other, so far as it belongs to their nature.
Matter itself, however, is still far more impassible than the qualities
are among each other, when they do not find themselves opposite.