It is indispensable to a Painter who would be thoroughly familiar
with the limbs in all the positions and actions of which they are
capable, in the nude, to know the anatomy of the sinews, bones,
muscles and tendons so that, in their various movements and
exertions, he may know which nerve or muscle is the cause of each
movement and show those only as prominent and thickened, and not the
others all over [the limb], as many do who, to seem great
draughtsmen, draw their nude figures looking like wood, devoid of
grace; so that you would think you were looking at a sack of walnuts
rather than the human form, or a bundle of radishes rather than the
muscles of figures.
489.
HOW IT IS NECESSARY TO A PAINTER THAT HE SHOULD KNOW THE INTRINSIC
FORMS [STRUCTURE] OF MAN.
The painter who is familiar with the nature of the sinews, muscles,
and tendons, will know very well, in giving movement to a limb, how
many and which sinews cause it; and which muscle, by swelling,
causes the contraction of that sinew; and which sinews, expanded
into the thinnest cartilage, surround and support the said muscle.
Thus he will variously and constantly demonstrate the different
muscles by means of the various attitudes of his figures, and will
not do, as many who, in a variety of movements, still display the
very same things [modelling] in the arms, back, breast and legs. And
these things are not to be regarded as minor faults.
How to acquire practice.
490.