A Treatise on Painting

Of the man who rests on both feet, and gives more weight to one than the other. Chapter CCLXIV.

When, from standing for a long time, a man has tired the leg upon which he is resting, he shifts part of his weight onto the other leg. However, this type of resting should only be depicted for those of a decrepit age, or in infancy, or truly in someone who is exhausted, because it demonstrates weariness or a lack of vitality original: "valetudine" — referring to the physical strength or health of the limbs. in the limbs. Therefore, one always sees a young man who is healthy and vigorous resting upon only one of his legs; and if he does place some weight upon the other leg, he does so only when he intends to begin a necessary movement, without which all motion is impossible—for motion is generated by inequality This is a fundamental principle of Leonardo's physics: balance (equality) is static, while movement (inequality) occurs when the center of gravity is shifted..

Of the posing of figures. Chapter CCLXV.

Figures that are at rest must always vary their limbs; that is, if one arm goes forward, the other should remain still or go backward. If the figure rests upon one leg, the shoulder that is above that leg should be lower than the other This is a classic description of "contrapposto," where the hips and shoulders tilt in opposite directions to maintain balance.. This is observed by men of good sense, who always naturally attend to the balancing original: "bilicare" — to poise or find a center of gravity. of a man upon his feet so that he does not collapse. Because when resting on one foot, the opposite leg—being bent—does not support the man; it is as if it were dead original: "come se fusse morta" — meaning it carries no weight.. Therefore, necessity dictates that the weight of the body from the legs upward must shift its center of gravity over the joint of the leg that supports it.