By making, however, another beginning, these things will be more apparent; for it must be considered, whether it is possible that there can be any continued motion or not, and, if it is possible, what it is; and what is the first of motions. For it is evident, that if it is necessary motion should always exist, and this is the first and continued motion, the first mover will move according to this motion, which is necessarily one and the same, and continued, and the first. But since there are three motions, one according to magnitude, another according to passive quality, and another according to place, which we call lation, it is necessary that lation should be the first; since it is impossible there should be increase, unless alliation had a prior subsistence; for that which is increased, is partly increased by the similar, and partly by the dissimilar; for the contrary is said to be aliment to the contrary: and every thing accedes, becoming similar to the similar. It is necessary, therefore, that the mutation into contraries should be alliation. If also a thing is changed in quality, it is necessary there should be that which produces the change in quality, and which makrs a thing from being hot in capacity, hot in energy. It is evident, therefore, that the thing which moves, does not subsist similarly, but at one time is nearer, and at another more remote from that which is changed in quality. But these cannot subsist without lation. If, therefore, it is necessary that motion should always exist, it is also necessary that lation should always be the first of motions. And if of lations, one is prior, and another posterior, it is neceasary that the first motion should be the first lation.
Again, the principle of all passions is condensation and rarefaction; for the heavy and the light, the soft and the hard, the hot and the cold, appear to be certain densities and rareties. But condensation and rarefaction are concretion and secretion, according to which generation also and corruption are predicated of essences or substances. It is also necessary, that things which grow together, or which are separated, should be changed according to place. The magnitude likewise of that which is increased or diminished, changes according to place. Further still, hence also; to those who consider the affair, it will be evident that lation is the first motion; for that which is first as in other things, so likewise in motion, may be predicated multifariously; for that is said to be prior, without which other things will not be, but which can itself exist without others; that also is said to be prior, which is first in time; and that which is first in essence. Hence, since it is necessary that motion should exist continually, and either that which is continuedor that which is successive may exist continually, but rather that which is continued; and it is better to be continued than successive; since likewise, we always conceive that what is better exists in nature, if it be possible for it to exist, and it is possible to be continued, which will be afterwards demonstrated, but is now supposed, and it is not possible that this can be any thing else than lation; this being the case, it is necessary that lation should be the first motion. For there is no necessity that a thing which is moved according to lation should either be increased, or changed in qualiiy, and therefore, neither that it should be generated or corrupted; but no one of these could exist, unless the continued motion exists which is produced by the first mover.
Farther still, lation also is the first motion in time; for perpetual nature can alone be moved with this motion. In each of those things, however, it may be said, which have generation, it is necessary that lation should be the last motion. For after a thing is generated, it is first necessary that there should be change in quality and increase; but lation is the motion of things, which are now perfect. In answer to this, it must be observed, that it is necessary something else should be prior, which is moved according to lation, and which is also the cause of generation to generated natures, not being generation itself; as that ,which generates it prior to that which is generated. But generation may seem to be the first of motions, because it is necessary that a thing should first be generated. This indeed takes place in each of the things which are generated; but it is necessary that something else should be moved prior to things which are generated, itself subsisting without being generated; and it is necessary that there should be something else prior to this. But since it is impossible that generation should be first (for if this were the case, every thing that is moved would be corruptible) it is evident, that no one of the successive motions can be prior. But I call successive motions increase, afterwards change in quality, diminution, and corruption; for all these are posterior to generation. Hence, if generation is not prior to lation, neither will any other mutation. In short, that which is generated appears to be imperfect, and to proceed to the principle; so that what is posterior in generation, is prior by nature. Lastly, lation is inherent in all things which are generated. Hence, some vital natures are entirely immoveable, through the want of an organ, as plants, and many genera of animals; but with others motion is present when they are perfect. If lation, therefore, is more inherent in things which have obtained more of nature, this motion also will be the first of the others according to essence: as well for the above reasons, as because that which is moved departs the least from essence of all motions, in being borne along. For according to this motion alone, nothing of the being of a thing is changed; as of that which is changed in quality, the quality is changed,and of that which is increased and diminished, the quantity. But it is especia1ly manifest, that the nature which itself moves itself, especially moves properly with local motion. But we say, that this is the principle of things which are moved and move, and is first to things that are moved; viz. that which itself moves itself. That lation, therefore, is the first of motions, is from these things evident.
