[bending] himself, that he makes himself sufficient to resist the applied weight. It is also seen in one who is about to fall backward on one of his lateral sides, that he always throws out the arm on the opposite side.

[316] On human motion. Book B, folio 15.
When you wish to make a man the mover of some weight, consider that the motions are to be made along different lines, that is, either from below upward with simple motion, as does one who, stooping, takes up the weight that, straightening himself, he wishes to raise; or when one wishes to drag something behind, or to push it forward, or you wish to pull downward with a rope that passes over a pulley. Here it is recalled that the weight of the man pulls as much as the center of his gravity is outside the center of his support; to this is added the force made by the legs and the bent back in straightening itself.
One never descends or ascends, nor ever walks along any line, without the rear foot raising the heel.

[317] On the motion created by the destruction of balance.
The motion created by the destruction of balance, that is, of equality, since nothing moves of itself that does not depart from its balance, and it becomes the faster, the more it removes itself from its aforesaid balance.

[318] On the balance of figures. Book A, folio 39.
If the figure rests upon one of its feet, the shoulder of the side that rests will always be lower than the other, and the pit of the throat will be above the middle of the leg that rests. And the same—