B. Instance

445. And if it be said that this belongs to more imperfect things (as animals) only according to a part of them, because they can be divided into two (namely into mover and moved), but if it be said that what is assumed about heavy and light things [sc. that they have an active power, n.444] is false and against the Philosopher’s intention (as it seems) in Physics 8.4.255a4-18, where he seems to give four reasons specifically against it (first by the fact that a heavy thing is not an animal, second by the fact that it cannot stop itself, third that it cannot move itself with diverse motions, fourth that it is continuous, that is, of the same kind in a part and in the whole, and such a thing cannot move itself), and in solving the question he says that ‘natural things have only a principle of undergoing with respect to motion and not a principle of acting’ - I show the opposite, first from authorities and second through reasons.