On the Force of Percussion

DE VI PERCUSSIONIS. CAP. II.

The fallacy of the Peripatetic reasoning is detected.

it can be replied with Aristotle to leave to the senses the fact that heavy objects and animals move by themselves, and that to seek a reason for this thing is the mark of a weak mind. Nevertheless, the adduced reasons seem easily able to be dissolved; for the agent and the patient, the builder and the built, are truly distinguished in some works of art and in some motions, such as projections and percussions. But in the works of nature, for the most part, the agent and the patient are not distinguished, for the same animastic substance as if it were to build, increase, and move the animal’s substance, and the same substance of a heavy body migrates and descends impelled by itself; and it is simultaneously in act and in potency while it operates, and the agent and patient are distinguished only by respect and reason, not by substance. Indeed, that the origin of this deception may be detected, it must be noted that the insufficiency of terms has given an opportunity for error, as the most learned Gassendi noted; for we say "to move" movere to move, which is the action of the agent, and "to be moved" moveri to be moved, which indicates passion. However, no word of the neuter gender is found in motion which might only sub-indicate the operation, the action, and the passion. And if indeed the usage of the common people, whose power and rule it should be to prescribe the laws of speaking, were to govern, then surely whatever is moved, as it sounds like a passion, ought to be moved by a mover as by an active cause. But it is known from elsewhere, on the contrary, that philosophers, obeying truth and the laws of nature, correct the common people and the usage of speech, introduce new words, and, in short, entirely despise vulgar modes of speaking. Yet, notwithstanding these, there are very many words which sub-indicate action and passion at the same time—namely, motion made by itself, as is operation, course, ascent, descent, and very many of this kind, in all of which operations edited by themselves are sub-indicated. Nor, furthermore, in artificial operations is the agent always distinguished from the patient, as the smith and the house, but these exist simultaneously in the same subject, as are choirs, armies, and automata original: "authoma". For in these, the same men are indeed the matter of the army and the choir, and likewise they are the agents operating; namely, the same men are those who soldier, and in the choir dance and sing. Likewise, in a clock, the same machine is the matter and at the same time the moving principle by which the hours are distinguished, and the remaining artificial motions are subsequently promoted; and in all these, or at least in the first movers—namely, in the animastic spirits and in the machine.