The is not any infinite mutation; for all mutation is from something into something, as well that which is in contradiction, as that which is in contraries. So that of those mutations which subsist according to contradiction, affirmation and negation are the boundary; as, for instance, of generation being is the boundary, and of corruption, non-being. But of those mutations which are in contraries, contraries are the boundaries: for these are the extremes of mutation. So that this will likewise be the case in all change according to quality; for change according to quality is from certain contraries. In like manner also, this will be true of increase and diminution: for the boundary of increase, is the end of a magnitude according to its proper nature; but of diminution, a departure from this magnitude. But lation is not thus bounded; for not all lation is in contraries. Since, however, it is not possible for a thing to be cut, unless it were possible that it might have been cut, (for the impossible is multifariously predicated), that which is attended with this impossibility cannot be cut. And, in short, if nothing can be generated, which might not once have been generated, neither can that which might not have been changed, be changed into that into which it might not have been changed. If, therefore, that which is home along, should be changed into any thing, it will also be possible that it might change. So that there will not be infinite motion, nor will a thing be impelled through infinite space, because it is impossible for the infinite to be passed through. It is evident, therefore, that there is not infinite mutation, so as not to be terminated by boundaries. It must be, however, considered, whether it be possible that there may be infinite mutation in such a manner, that being one and the same, it may be infinite in time: for not being one, nothing perhaps hinders this from taking place; as, for instance, if change, according to quality, should be after lation, ad increase after change in quality, and again generation: for thus there will always be motion in time, but not one motion; because there is not one motion from all these. So that it is not possible there should be one motion infinite in time, except the motion which is in a circle.
