He stood admiring the conceptions and the craftsmanship of those thirteenth century glass-workers, their emphatic language, necessary at such great heights, the way in which they had made the pictures legible from a distance by introducing a single figure in each, whenever that was possible, and painting it in massive outline, with contrasting colours, so as to be easily taken in at a glance when seen from below.

But the triumph of this art was neither in the choir, nor in the transepts of the church, nor in the nave; it was at the entrance, on the inner side of the wall, where on the outside stood the statues of the nameless queens.  Durtal delighted in this glorious show, but he always postponed it a little to excite himself by expectancy, and revel in the leap of joy it gave him, repetition of the sensation not having yet availed to weaken it.

On this particular day, under a sunny sky, these three windows of the twelfth century blazed with splendour with their broad short blades, the blade of a claymore, flat wide panels of glass under the rose that held the most prominent place over the west door.

It was a twinkling sheet of cornflowers and sparks, a shifting maze of blue flames—­a paler blue than that in which Abraham, at the end of the nave, brandished his knife; this pale, limpid blue resembled the flames of burning punch and of the ignited powder of sulphur, and the lightning flash of sapphires, but of quite young sapphires, as it were, still infantine and tremulous.  And in the right hand pointed window he could distinguish in burning red the Stem of Jesse—­figures piled up espalier fashion, in the blue fire of the sky; while to the left and in the middle, scenes were shown from the Life of Jesus—­the Annunciation, Palm Sunday, the Transfiguration, the Last Supper, and the Supper at Emmaus; and above these three windows Christ hurled thunder from the heart of the great rose, the dead emerged from their graves at the trumpet-call, and St. Michael weighed souls.

“How did the glass-makers discover and compound that twelfth century blue?” wondered Durtal.  “And why have their successors so long lost it, as well as their red?

“In the twelfth century glass-painters made use chiefly of three colours; first, blue—­that ineffable, uncertain sky-blue which is the glory of the Chartres windows; then red—­a purplish red, full and important; and green—­inferior in quality to the two others.  For white they preferred a greenish tinge.

“In the following century the palette is more extensive, but the stain is darker; the glass, too, is thicker.  And yet, what a glowing blue of pure, bold sapphire tone the artists of the furnace had at their command, and what a fine red they used, the colour of fresh blood!  Yellow, of which they were less lavish, was, if I may judge from the robe of a king near the Abraham, in a window by the transept, a daring hue of bright lemon.  But apart from these three colours, which have a sort of resonance, and burst forth like songs of joy in these transparent pictures, others grow more sober; the violets are like Orleans plums or purple egg-fruit, the browns are of the hue of burnt sugar, the chive-coloured greens turn dark.