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