“But what masterpieces of colour they achieved by the harmony and contrast of these tones, and with what skill did they handle the lead-lines, emphasizing certain details, punctuating and dividing these paragraphs of flame as if with lines of ink.

“And another thing which is amazing is the perfect agreement of all these various crafts, practised side by side, treating the same subjects, or supplementing each other—­each, by its own mode of expression, under one guiding mind, contributing to the whole; with what a sense of fitness, with what skill were the posts distributed, the places assigned to each as beseemed the purpose of his craft, the requirements of his art.

“Architecture having finished the lower portion of the edifice, retires into the background to make way for Sculpture, giving it the fine opportunity of the doorways; and Sculpture, hitherto invisible at excessive heights, as a mere accessory, suddenly finds itself supreme.  With due sense of justice it now comes forward where it can be seen, and the sister art retires, leaving it to address the multitude, giving it the noblest framework in those arched doorways, imitating a deeper perspective by their concentric arches, diminishing and retreating to the door-frames.

“In other instances Architecture does not give everything to one art, but divides the bounty of her great facade between sculpture and painting; reserving to the former the hollows and nooks where statues may find niches, and giving to glass-painters the tympanum of the great door, where at Chartres the image-maker has displayed the Triumph of Christ.  This we see in the great west doors of Tours and of Reims.

“This plan of substituting glass for bas-reliefs had its disadvantages; seen from outside—­their wrong side—­these diaphanous pictures look like spiders’ nets on an enormous scale and thick with dust.  With the light on them the windows are, in fact, grey or black; it is only by going inside and looking back that their fire can be seen flashing; the outside is here sacrificed to the inside.  Why?

“Perhaps,” said Durtal, answering himself, “it is symbolical of the soul having light inwardly, an allegory of the spiritual life—­”

He took in all the windows of the nave with a rapid glance, and it struck him that their effect was a combination of the prison and the grave, with their coals of fire burning behind iron bars, some crossed like the windows of a gaol, and others twisting like black twigs and branches.  Is not glass painting of all arts that in which God does most to help the artist, the art which man, unaided, can never make perfect, since the sky alone can give life to the colours by a beam of sunshine, and lend movement to the lines?  In short, man fashions the form, prepares the body, and must wait till God infuses the soul.