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2. In the Second, he examines the Changes, which he knows in Matter, and makes it his business to explicate all those that respect Quantity, Qualities and Forms, by Local Motion, esteeming their needs no others
3. In the third, he explains the Motion of Artificial Engins, and that of Natural ones, by one and the same Cause; endeavouring among other things to shew, that the Body of an Animal is moved after the same manner with a Watch. That cause of motion he makes the Materia subtilis; and the finer or subtiler that is, the better and fitter he conceives it to be to preserve Motion.
4. In the Fourth, he teaches, that though Experience seems to evince, that the Soul moves the Body, and that one Body moves an other; yet there is nothing, but God, that can produce any motion in the World, and all other Agents, which we believe to be the Cause of this or that Motion, are no more but the Occasion thereof. In doing this, he advances certain Axioms, and Conclusions, which are in short,
a. The Axioms: That no substance has that of it self, which it can loose, without ceasing to be, what it is: That every body may loose of its motion, till it have no more left, without ceasing to be a Body: That we cannot conceive but two sorts of substances, vid. a Spirit (or That which thinketh) and a Body, wherefore they must be considered as the Causes of all, that happens, and what cannot proceed from the one, must necessarily be adscribed to the other; That to Move, or to cause motion, is an Action: That an Action cannot be continued but by the Agent, who began it.
b. The Conclusions; That no Body hath Motion of it self: That the First Mover of Bodies is not a Body: That it cannot be but a Spirit, that is the First Mover; That it cannot be but the same Spirit, who has begun to move Bodies, that continues to move.
In the Fifth, He treats of the Union of the Body and Soul, and the manner, how they act one upon the other; and esteems it not more difficult to conceive the Action of Spirits upon Bodies, and of Bodies upon Spirits, than to conceive the Action of Bodies upon Bodies: the cause of the great difficulty in understanding the two former; arising (according to him) from thence, that we will conceive the one by the other, not considering, that every thing acting according to its own nature, we shall never know the action of one Agent, if we will examine it by the notions we have of another, that is of a quite differing nature. Here he notes, that the Action of Bodies upon Bodies is not
