sets the living being in motion, and each of them is produced by various kinds of motion. Aristotle likewise asserts that everything which is created must, before its actual creation, have existed in potentia. By inferences drawn from this assertion he seeks to establish his proposition, viz., The thing that moves is finite, and its path finite; but it repeats the motion in its path an infinite number of times. This can only take place when the motion is circular, as has been stated in Proposition XIII. Hence follows also the existence of an infinite number of things which do not co-exist but follow one after the other.
Aristotle frequently attempts to establish this proposition; but I believe that he did not consider his proofs to be conclusive. It appeared to him to be the most probable and acceptable proposition. His followers, however, and the commentators of his books, contend that it contains not only a probable but a demonstrative proof, and that it has, in fact, been fully established. On the other hand, the Mutakallemim try to prove that the proposition cannot be true, as, according to their opinion, it is impossible to conceive how an infinite number of things could even come into existence successively. They assume this impossibility as an axiom. I, however, think that this proposition is admissible, but neither demonstrative, as the commentators of Aristotle assert, nor, on the other hand, impossible, as the Mutakallemim say. We have no intention to explain here the proofs given by Aristotle, or to show our doubts concerning them, or to set forth our opinions on the creation of the universe. I here simply desire to mention those propositions which we shall require for the proof of the three principles stated above. Having thus quoted and admitted these propositions, I will now proceed to explain what may be inferred from them.
CHAPTER I
According to Proposition XXV., a moving agent must exist which has moved the substance of all existing transient things and enabled it to receive Form. The cause of the motion of that agent is found in the existence of another motor of the same or of a different class, the term "motion," in a general sense, being common to four categories (Prop. IV.). This series of motions is not infinite (Prop. III.); we find that it can only be continued till the motion of the fifth element is arrived at, and then it ends. The motion of the fifth element is the source of every force that moves and prepares any substance on earth for its combination with a certain form, and is connected with that force by a chain of intermediate motions. The celestial sphere [or the fifth element] performs the act of locomotion which is the first of the several kinds of motion (Prop. XIV.), and all locomotion is found to be the indirect effect of the motion of this sphere; e.g., a stone is set in motion by a stick, the stick by a man's hand, the hand by the sinews, the sinews by the muscles, the muscles by the nerves, the nerves by the natural heat of the body, and the heat of the body by its form. This is undoubtedly the immediate motive cause, but the action of this immediate cause is due to a certain design, e.g., to bring a stone into a hole by striking against it with a stick in order to prevent the draught from coming through the crevice. The motion of the air that causes the draught is the effect of the motion of
