must also be a point which is unmoved, and this is our meaning when we

speak of a point which is in potency one, but which becomes two in

actual exercise. Now if the arm were the living animal, somewhere in

its elbow-joint would be situate the original seat of the moving soul.

Since, however, it is possible for a lifeless thing to be so related

to the hand as the forearm is to the upper (for example, when a man

moves a stick in his hand), it is evident that the soul, the

original of movement, could not lie in either of the two extreme

points, neither, that is, in the last point of the stick which is

moved, nor in the original point which causes movement. For the

stick too has an end point and an originative point by reference to

the hand. Accordingly, this example shows that the moving original

which derives from the soul is not in the stick and if not, then not

in the hand; for a precisely similar relation obtains between the hand

and the wrist, as between the wrist and the elbow. In this matter it

makes no difference whether the part is a continuous part of the

body or not; the stick may be looked at as a detached part of the

whole. It follows then of necessity that the original cannot lie in

any individual origin which is the end of another member, even

though there may lie another part outside the one in question. For

example, relatively to the end point of the stick the hand is the

original, but the original of the hand's movement is in the wrist. And

so if the true original is not in the hand, be-there is still

something higher up, neither is the true original in the wrist, for

once more if the elbow is at rest the whole part below it can be moved

as a continuous whole.

9



Now since the left and the right sides are symmetrical, and these

opposites are moved simultaneously, it cannot be that the left is

moved by the right remaining stationary, nor vice versa; the

original must always be in what lies above both. Therefore, the