54 THE STONES OF VENICE I. Pride of Science

them, would be an infinite refreshment to his mind; a minor subject of interest, to which it might turn when jaded with comfortless labour, or exhausted with feverish invention, and yet which would never interfere with its higher functions, when it chose to address itself to them. Even a considerable amount of manual labour, sturdy colour-grinding and canvas-stretching, would be advantageous; though this kind of work ought to be in great part done by pupils. For it is one of the conditions of perfect knowledge in these matters, that every great master should have a certain number of pupils, to whom he is to impart all the knowledge of materials and means which he himself possesses, as soon as possible; so that, at any rate, by the time they are fifteen years old, they may know all that he knows himself in this kind; that is to say, all that the world of artists know, and his own discoveries besides, and so never be troubled about methods any more. Not that the knowledge even of his own particular methods is to be of purpose confined to himself and his pupils, but that necessarily it must be so in some degree; for only those who see him at work daily can understand his small and multitudinous ways of practice. These cannot verbally be explained to everybody, nor is it needful that they should; only let them be concealed from nobody who cares to see them; in which case, of course, his attendant scholars will know them best. But all that can be made public in matters of this kind should be so with all speed, every artist throwing his discovery into the common stock, and the whole body of artists taking such pains in this department of science as that there shall be no unsettled questions about any known material or method: that it shall be an entirely ascertained and indisputable matter which is the best white, and which the best brown; which the strongest canvas, and safest varnish; and which the shortest and most perfect way of doing everything known up to that time; and if any one discovers a better, he is to make it public forthwith. All of them taking care to embarrass themselves with no theories or reasons for anything, but to work empirically only: it

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