“Seeing that Design, the parent of our three arts, Architecture, Sculpture, and Painting, having its origin in the intellect, draws out from many single things a general judgment, […] we may conclude that design is not other than a visible expression and declaration of our inner conception and of that which others have imagined and given form to in their idea. And from this, perhaps, arose the proverb among the ancients ‘ex ungue leonem‘ when a certain clever person, seeing carved in a stone block the claw only of a lion, apprehended in his mind from its size and form all the parts of the animal and then the whole together, just as if he had had it present before his eyes. […]

      “But let this be as it may, what design needs, when it has derived from the judgment the mental image of anything, is that the hand, through the study and practice of many years, may be free and apt to draw and to express correctly, with the pen, the silverpoint, the charcoal, the chalk, or other instrument, whatever nature has created. For when the intellect puts forth refined and judicious conceptions, the hand which has practised design for many years, exhibits the perfection and excellence of the arts as well as the knowledge of the artist. […]

      “The masters who practise these arts have named or distinguished the various kinds of design according to the description of the drawing which they make. Those which are touched lightly and just indicated with the pen or other instrument are called sketches, as shall be explained in another place. Those, again, that have the first lines encircling an object are called profiles or outlines.

      “All these, whether we call them profiles or otherwise, are as useful to architecture and sculpture as to painting. Their chief use indeed is in Architecture, because its designs are composed only of lines, which so far as the architect is concerned, are nothing else than the beginning and the end of his art, for all the rest, which is carried out with the aid of models of wood formed from the said lines, is merely the work of carvers and masons.

      “In Sculpture, drawing is of service in the case of all the profiles, because in going round from view to view the sculptor uses it when he wishes to delineate the forms which please him best, or which he intends to bring out in every dimension, whether in wax, or clay, or marble, or wood, or other material.

      “In Painting, the lines are of service in many ways, but especially in outlining every figure, because when they are well drawn, and made correct and in proportion, the shadows and lights that are then added give the strongest relief to the lines of the figure and the result is all excellence and perfection. […] When he has trained his hand by steady practice in drawing (figures in relief, plaster casts), let him begin to copy from nature and make a good and certain practice herein, with all possible labour and diligence, for the things studied from nature are really those which do honour to him who strives to master them, since they have in themselves […] that simple and easy sweetness which is nature’s own, and which can only be learned perfectly from her, and never to a sufficient degree from the things of art. Hold it moreover for certain, that the practice that is acquired by many years of study in drawing, as has been said above, is the true light of design and that which makes men really proficient.”