That, when a group of young and enthusiastic artists, eager to overturn barriers, are found painting more or less together, it is not so easy to unravel the tangle of influences and draw hard-and-fast lines everywhere, one or two modern examples much nearer to our own time may roughly serve to illustrate. Take, for instance, the friendship that developed itself between the youthful Bonington and the youthful Delacroix while they copied together in the galleries of the Louvre: the one communicating to the other something of the stimulating quality, the frankness, and variety of colour which at that moment distinguished the English from the French school; the other contributing to shape, with the fire of his romantic temperament, the art of the young Englishman who was some three years his junior. And with the famous trio of the P.R.B.--Millais, Rossetti, and Mr. Holman Hunt--who is to state _ex cathedra_ where influence was received, where transmitted; or whether the first may fairly be held to have been, during the short time of their complete union, the master-hand, the second the poet-soul, the third the conscience of the group? A similar puzzle would await him who should strive to unravel the delicate thread which winds itself round the artistic relation between Frederick Walker and the noted landscapist Mr. J.W. North. Though we at once recognise Walker as the dominant spirit, and see his influence even to-day, more than twenty years after his death, affirmed rather than weakened, there are certain characteristics of the style recognised and imitated as his, of which it would be unsafe to declare that he and not his companion originated them. In days of artistic upheaval and growth like the last years of the fifteenth century and the first years of the sixteenth, the _milieu_ must count for a great deal. It must be remembered that the men who most influence a time, whether in art or letters, are just those who, deeply rooted in it, come forth as its most natural development. Let it not be doubted that when in Giorgione's breast had been lighted the first sparks of the Promethean fire, which, with the soft intensity of its glow, warmed into full-blown perfection the art of Venice, that fire ran like lightning through the veins of all the artistic youth, his contemporaries and juniors, just because their blood was of the stuff to ignite and flame like his own.