If you intend to become a Proficient, be sure never to design any thing slightly or in haste; but take time to consider, with regard to lights, which parts receive the strongest, and in shadows which are the deepest; observe how these mingle together, and in what quantity, still comparing the one with the other. As to the Contours, consider towards what part they are to be directed, what quantity of light and shadow meet within the Lines, where they are more or less strong, larger or smaller; and lastly take care that your lights and shadows do not terminate abruptly, but that they fall softly into one another, and at last lose themselves insensibly like Smoke. After you have once habituated your self to be thus punctual and exact in your Designs, Expedition and Dispatch will come apace.