That the master or masters of Canterbury and Sens came to Chartres is, I think, certain; the Canterbury tradition is traceable in so much of the work. Here I imagine he or they ended their life's work, leaving their pupils and their pupils' successors to carry it on in the later style which they developed as they went along. One of these, no doubt, was that Clement of Chartres who signed his name in the window at Rouen which Mr. Saint has sketched in Plate XIV. I think I can trace his hand in some of the windows on the south side of the nave at Chartres, in the treatment of the mosaic diaper in which various shades of blue have been so skilfully blended as to produce, as at Rouen, a lovely play and ripple of colour over the whole surface of the window. Perhaps the most notable development of the style at Chartres is the increase in the use of mosaic diaper, of the kind illustrated in Plate VIII., as a setting for the medallions, instead of the leafy scroll work formerly used. At Canterbury the mosaic diaper setting is the exception, only occurring in one window; at Sens it is introduced tentatively, but at Chartres it is the rule. The scroll-work filling only occurs, I think, in three windows of the lower tier. One of these is the St. Eustace window already mentioned, which to me is strongly reminiscent of Canterbury work--more so, indeed, as far as the medallions go, than the similar one at Sens. [Illustration: PLATE XVII DETAILS FROM WINDOWS IN THE NORTH AISLE OF NAVE, YORK MINSTER Fourteenth Century] [Sidenote: The four extremities.] It is only at the four extremities of the Cathedral at Chartres that we find any connected idea governing the choice of subjects. The three twelfth century windows were already, as I have said, devoted to the ancestry and life of Christ, and the thirteenth century rose window above them shows His second coming. The seven great lancets of the apse are given up to the glorification of the Virgin, the especial patroness of Chartres. The north rose and the lights below it seem to show the human ancestry of Christ culminating in Saint Anne and the Virgin, while opposite in the south transept is the Christ of the Apocalypse. In other parts of the church the choice of theme seems to have been left to the taste of the donors, subject only to the general arrangement of medallion windows in the lower tier and huge single figures in the clerestory lights. Thus in the lower windows we find the story of Noah next to that of St. Lubin, Bishop of Chartres; the story of St. Eustace next that of Joseph.