De Rervm Natvra Constantivm Scientia, Principiis Et Affectionibvs Commvnibvs, Dispvtatio

XXII. Nor, indeed, if matter brings not only a passive but also an active power with form to incite motion (which is necessary if, as the common opinion holds, form is truly said not to be the perfect principle of operating) must one therefore deny that nature is a passive principle of motion. From which it happens that things which have only a passive principle of their own motion are nonetheless to be said both to be moved by nature and to have a nature.

XXIII. From these things, it is gathered what things consist by nature; namely, that it is necessary that all perfect substances—whether they be corruptible or free from corruption, whether they be animate or lack a soul—have a nature. From which it is effected that the heavens also have a nature and are moved by nature, even if they are moved by angels, as it pleases the Theologians. For it is not repugnant that they be moved by themselves simultaneously; for the fact that a thing is moved by itself only causes that it can be moved without the impulse of angels, which is not an absurdity. Even if it were, at least this—that the heaven is moved by angels according to its own propensity—could seem sufficient for it to have a nature and be moved by it, which is perceived from the antecedents.

And this much on nature. It is now consequent that we treat of matter and form, which are comprehended under the name of nature.

CHAPTER III.

ON MATTER.

XXIV. Relying on experience, philosophers believed that a natural agent produces no effect except in some other distinct and certain thing, which through the continued action of the agent would approach more and more toward the likeness of the agent. Hence, they then suspected that what is produced by the agent needs a subject subsisting of itself. From this, they called that which remains—not only that which is produced in the subject, but something remaining—"matter." Aristotle, later in age than these, added that what is produced in the subject is one thing that is external and alien to the nature of the subsistent, and another internal, which would be a part of the subsistent; and from this, gathering that the whole subject subsisting of itself does not always persevere, but only a part of it, he named this, and not the whole subsistent, "matter."