When you understand the make of a Human Body, its Members, Jonctures, and the several Positions these are capable of, apply your self to the Study of Motion. And here you will find it of considerable Service to draw slight Sketches, of any thing in the Actions of those about you, these may be worthy of notice; taking care by the way that the Persons be not apprized of what you are doing, since by this means they will infallibly come short of that Force and Spirit in the Action, which otherwise they wou'd express. Thus when two Men are enraged, with what Violence and Fury do they rush upon each other? Their Eye-brows move with briskness, and their Arms swing impetuously every way, and every Gesture and Motion they show, confesses the Rage, Choler, and Passion that transports them. Now it will be impossible to make a Model express the Zeal and Fervour, with which a Genuine Rage is attended; or even to represent the Effects of any Real Passion, as Grief, Admiration, Fear, Joy, or the like: A Man is not so much Master of his Passions as to raise and lay them when he pleases. Let a Painter therefore take his Motions and Attitudes from Nature her self, rather than from those who wou'd appear to Mimick her; always remembring, that a just Contour, and a lively Expression are the most Important parts of his Art.