LI. This definition is incumbered with greater difficulties than the antecedent ones. All the modern philosophers oppose it, although for distinct and contrary reasons. Gassendo, father Maignan, and the other atomists, attribute motion _ab intrinsico_ to atoms, from which dogma it will follow, that motion _ab intrinsico_, is not distinctly peculiar to living animals. The Cartesians are very positive in maintaining, that nothing can give motion to itself, but that all motion in the universe, proceeds from that impulse, which God in the beginning gave to matter, which does, and ever will subsist, without being impaired or injured; and that by virtue of that impulse, motion is communicated from one part of matter to another; so that all which was before at rest, upon its beginning to move, received its impulse from some other body which was in motion before, and transferred its influence to that which was then at rest; and either partly, or in the whole, gave it the power of beginning to move; and they say further, that man, which is the only living corporeal entity they admit, when he moves, cannot be properly said to give motion to his members, but only directs their motion by his will, in virtue of the power antecedently impressed by the impulse of other bodies on the animal spirits. LII. It cannot be denied, that this doctrine is terribly fortified, by the celebrated maxim of Aristotle, which says, _that every thing that moves, is set in motion by something else_: and although the followers of the common opinion, explain this maxim, so as to render it not incompatible with the definition they give of living entities, there results from this explanation, the inconvenience, that it weakens the principal force of the axiom which they avail themselves of to prove the existence of a first mover, to stimulate a body at rest; for if we suppose, that a living entity has the power of moving itself, we cannot maintain the necessity of a divine influence to produce this motion, without admitting at the same time, the existence of a first mover in other respects, to be established. Thus it seems to me, that the Cartesians can with some colour of reason pretend, that religion is interested in understanding the axiom in all the rigour, which they profess to understand it themselves.