A Treatise on Painting/Chapter 32
Appearance
Chap. XXXII.—Memorandum to be observed by the Painter.
Note down which muscles and tendons are brought into action by the motion of any member, and when they are hidden. Remember that these remarks are of the greatest importance to painters and sculptors, who profess to study anatomy, and the science of the muscles. Do the same with children, following the different gradations of age from their birth even to decrepitude, describing the changes which the members, and particularly the joints, undergo; which of them grow fat, and which lean.