TWELFTH CENTURY GLASS The few examples I have mentioned are the only ones which can with any probability be dated from the eleventh century, but of twelfth century work much more remains. [Sidenote: Poitiers.] The window at Poitiers in Plate II. shows little if any change in style from the Le Mans window in Plate I. It is still almost pure Byzantine, and if I were to judge by style alone I should place this window very early indeed. A fragment of an inscription has, however, been found on it--DITHANC ... BLAS,--which has been thought to mean that the window was the gift of one Maurice de Blason, who became Bishop of Poitiers in 1198. If so, and if we are right in identifying the Le Mans window with Bishop Hoel's glazing, a whole century separates the two. The probable explanation is that the Byzantine style had lingered on in the south-east of France, as it may well have done, whereas north of the Loire a school had by this time arisen, and had been flourishing for many years, which was producing work both in France and England of a very different and far more advanced character. [Sidenote: The school of Chartres, St. Denis, and Canterbury.] The twelfth and early thirteenth century windows at Chartres, St. Denis, Canterbury and Sens show such resemblance to each other that there can be little doubt of their common origin. As, however, their execution covers a period of at least seventy years, one man cannot have been responsible for them all. Probably they represent the work of a group of men working together--perhaps never more than half a dozen at one time--under a master who was trained by his predecessor, and who in turn would be succeeded in the leadership by the best of his pupils. Several of these masters in succession must have been men of genius, and thus between them they evolved a style which, carried on by a succession of lesser men, governed design in stained glass for a century to come. [Illustration: PLATE VII BORDER, FROM THE TRINITY CHAPEL, CANTERBURY Twelfth or early Thirteenth Century] The rise of this school is the first of the periodic impulses to which I have referred, and the work they produced was, for its dignity and grandeur, unequalled for two hundred years--if it has ever been equalled at all. The figure of Methuselah or "Matusale" in Plate III., which is one of the few remaining of the original figures once in the choir clerestory at Canterbury (it is now in the S. Transept), is a good example of their work, and a comparison of it with the Poitiers window (which is actually later in date but in the older style) shows the greatness of the change they effected. The change is, in fact, that from ancient to modern art: from Byzantine, the last lingering survival of the great classic tradition of Greece, to Gothic, the first expression of the art of the modern world.