30. Drawing: that is to say, the expression by gradation of light, either of form or space. Again I thus give you a statement wholly adverse to the vulgar opinion of him. You will find that statement early in the first volume of "Modern Painters," and repeated now through all my works these twenty-five years, in vain. Nobody will believe that the main virtue of Turner is in his drawing. I say "the main virtue of Turner." Splendid though he be as a colorist, he is not unrivaled in color; nay, in some qualities of color he has been far surpassed by the Venetians. But no one has ever touched him in exquisiteness of gradation; and no one in landscape in perfect rendering of organic form. 31. I showed you in this drawing, at last Lecture, how truly he had matched the color of the iron-stained rocks in the bed of the Ticino; and any of you who care for color at all cannot but take more or less pleasure in the black and greens and warm browns opposed throughout. But the essential value of the work is not in these. It is, first, in the expression of enormous scale of mountain and space of air, by gradations of shade in these colors, whatever they may be; and, secondly, in the perfect rounding and cleaving of the masses alike of mountain and stone. I showed you one of the stones themselves, as an example of uninteresting outline. If I were to ask you to paint it, though its color is pleasant enough, you would still find it uninteresting and coarse compared to that of a flower, or a bird. But if I can engage you in an endeavor to draw its true forms in light and shade, you will most assuredly find it not only interesting, but in some points quite beyond the most subtle skill you can give to it. 32. You have heard me state to you, several times, that all the masters who valued accurate form and modeling found the readiest way of obtaining the facts they required to be firm pen outline, completed by a wash of neutral tint. This method is indeed rarely used by Raphael or Michael Angelo in the drawings they have left us, because their studies are nearly all tentative--experiments in composition, in which the imperfect or careless pen outline suggested all they required, and was capable of easy change without confusing the eye. But the masters who knew precisely before they laid touch on paper what they were going to do--and this may be, observe, either because they are less or greater than the men who change; less, in merely drawing some natural object without attempt at composition, or greater in knowing absolutely beforehand the composition they intend; it may be, even so, that what they intend, though better known, is not so good:--but at all events, in this anticipating power Tintoret, Holbein and Turner stand, I think, alone as draughtsmen; Tintoret rarely sketching at all, but painting straight at the first blow, while Holbein and Turner sketch indeed, but it is as with a pen of iron and a point of diamond.