The arched form of the top of the background shows how it once fitted a clerestory light, though doubtless with a border, and the space above has been filled with scroll work of, I think, the same date, which may have come from some of the medallion windows in the choir aisles. The two medallion windows in the north choir aisle formed part, as we know from an old MS. still in existence, of a series of twelve dealing with the life and parables of our Lord. In style they very closely resemble the St. Denis work, perhaps a little further developed. Some of the medallions, indeed, are almost identical with those at St. Denis, notably that of the Magi on horseback following the star. The figures are tall and dignified, and both for drawing and decorative placing are far better than much work of the succeeding century. The Calling of Nathaniel is a particularly good panel. The westernmost of the two windows still retains the early arrangement found at Chartres, the iron-work consisting simply of straight bars dividing it into a series of regular squares, which are filled alternately with circular and square medallions. [Illustration: PLATE X THE BIG ANGEL, FROM THE CLERESTORY OF THE APSE, CHARTRES CATHEDRAL Thirteenth Century] The other one of the two has bent iron-work of a very simple design, consisting simply of four circles connected by straight bars, thus marking the transition from one form to another; which is another reason for dating these windows between the west windows of Chartres, where the iron-work is all straight, and those at Sens, where it is nearly all bent. The small scale-sketch in the corner of Plate IV. shows the arrangement of the iron-work and the medallions. The panel of Noah in the Ark is from one of the semicircles on the left side of the window. The spaces between the medallions are filled up with beautiful foliated scroll work, on a ruby ground of the same character as that round the head of Methuselah. The arrangement of their subjects is so interesting, forming one of the first and most complete examples of a "type and antitype" window, that I shall describe it in some detail. In each of these two windows the upper two-thirds, or thereabouts, of the glass is in its original position, while the lower panels, smashed by the pike of "Blue Dick," who seems at this point to have got tired of going up his ladder, have been filled with subjects from other windows of the series. Down the centre run the subjects from the life of Christ, while on each side are the "types" or subjects from the Old Testament which illustrate it. Thus the westernmost of the two, once the second of the series, begins at the top with the Magi following the star, while on one side is Balaam, with the words of his prophecy, "There shall come a star out of Jacob, etc.," and on the other Isaiah, with the words, "The Gentiles shall come to Thy light, and kings to the brightness of Thy rising."