The quality of such sights as these, as I have more than once repeated, requires to be diligently sought for, and extricated from many things which overlay or mar it, throughout nearly the whole of Florentine Renaissance painting. But by good luck there is one painter in whom we can enjoy it as subtle, but also as simple, as in the hills and mountains outlined by sunset or gathered into diaphanous folds by the subduing radiance of winter moon. I am speaking, of course, of Pier della Francesca; although an over literal school of criticism stickles at classing him with the other great Florentines. Nay, by a happy irony of things, the reasons for this exclusion are probably those to which we owe the very purity and perfection of this man's Tuscan quality. For the remoteness of his home on the southernmost border of Tuscany, and in a river valley--that of the Upper Tiber--leading away from Florence and into Umbria, may have kept him safe from that scientific rivalry, that worry and vexation of professional problems, which told so badly on so many Florentine craftsmen. And, on the other hand, the north Italian origin of one of his masters, the mysterious Domenico Veneziano, seems to have given him, instead of the colouring, always random and often coarse, of contemporary Florence, a harmonious scheme of perfectly delicate, clear, and flower-like colour. These two advantages are so distinctive that, by breaking through the habits one necessarily gets into with his Florentine contemporaries, they have resulted in setting apart, and almost outside the pale of Tuscan painting, the purest of all Tuscan artists. For with him there is no need for making allowances or disentangling essentials. The vivid organic line need not be sought in details nor, so to speak, abstracted: it bounds his figures, forms them quite naturally and simply, and is therefore not thought about apart from them. And the colour, integral as it is, and perfectly harmonious, masses the figures into balanced groups, bossiness and bulk, detail and depth, all unified, co-ordinated, satisfying as in the sun-merged mountains and shelving valleys of his country; and with the immediate charm of whiteness as of rocky water, pale blue of washed skies, and that ineffable lilac, russet, rose, which makes the basis of all southern loveliness. One thinks of him, therefore, as something rather apart, a sort of school in himself, or at most with Domenico, his master, and his follower, della Gatta. But more careful looking will show that his greatest qualities, so balanced and so clear in him, are shared--though often masked by the ungainlinesses of hurried artistic growth--by Pollaiolo, Baldovinetti, Pesellino, let alone Uccello, Castagno, and Masaccio; are, in a word, Tuscan, Florentine. But more than by such studies, the kinship and nationality of Pier della Francesca is proved by reference to the other branches of Tuscan art: his peculiarities correspond to the treatment of line