It is the same also with walking and the other kinds of locomotion. For though all locomotion is a motion from one place to another, yet there are distinct kinds of locomotion, as flying, walking, leaping, etc. Nay, not only so, but even in walking itself there are differences, for the whence and whither are not the same in the entire course and in a portion of the course, or in this portion and in that, nor is crossing this line the same as crossing that; for you do not cross a line simply, but a line that is in a given place, and this line is in a different place from that I must refer to my other works 247 for a detailed discussion of motion; but it seems that it is not complete at any moment, but that its several parts are incomplete, and that they are specifically different from one another, the whence and whither being a specific difference.