The advent of the Van Eycks is the most important landmark in the history of painting in northern Europe. With them we open an entirely new chapter, for although the value of oil in various inferior processes of the art had been ascertained and availed of at an earlier period, it was entirely due to their long and painstaking experiments that its use was perfected as the vehicle of colouring matter in picture-painting. Unfortunately, time and its worst incidentals have obliterated the evidence which would have enabled us to follow the development of this new method, just as they have robbed us of all the earlier work of its original expounders, leaving us at the same time much too inconsiderable remains for a comprehensive survey of the school of which they were the finished product. It is a disconcerting experience to encounter primarily the lifework of two such eminent painters at a stage when they were already in the plenitude of their powers, and an experience that must always tax the ingenuity of the student and critic of their art. Particularly is this the case in respect of the elder brother, for the ascertained facts of Hubert's history are restricted to the last two years of his life (1425-26), while of the masterpieces he bequeathed to posterity only one can be said to be absolutely authenticated, though of others generally ascribed to him several may safely be accepted as genuine. John's career, on the other hand, can be traced back to 1424, but the chronology from that date to his death in 1441 is fairly ample, while he has left us a rich heritage of attested paintings to exemplify the varying aspects of his remarkable genius. [Illustration: PLATE II.--CHOIR OF ANGELS (By Hubert van Eyck) The first dexter lateral panel in the upper zone of the interior of the Great Polyptych: now in the Royal Gallery, Berlin. Painted in or before 1426. See page 31.]