The retro-choir, far too short and wide to be judged as an avenue of stone, is still more dependent for its effect on its glass. As most of that glass luckily remains, it is a miracle of airy splendour; one may see from it what were the objects, and how great the success of the much-maligned Perpendicular architects at their best. It is still the custom to regard Perpendicular architects as altogether inferior to their predecessors; an opinion partly arising, no doubt, from Mr Ruskin's eloquent exposition of the principle that beauty of detail is the most vital and important part of architecture; and partly from the general idea that older work is always better than later. But Perpendicular artists were not altogether retrogressive. In some respects they adapted their design more completely to their material than the older men. Their woodwork, for instance, completely shook off the forms of stone. Their glass, in spite of all that has been said, is better decoration of a given space than the patterns of the Decorated period. This is particularly evident in the nave and choir of the minster, for the original glass remains on many of the windows practically undisturbed. The earlier glass is more delicate, and purer in colour. Its designs are often more interesting pictorially. Look at the window simply as an isolated example of stained glass, and you will certainly prefer the earlier work. Look at it as a patch in a whole system of decoration, and you will be inclined to prefer the later. The wonderful success, as decoration of fragments of ancient stained glass pieced together almost at random, goes to prove, almost as clearly as the pictorial errors of modern designers, that a stained glass window should be conceived, not as a picture, hardly even as a pattern, but as a simple arrangement of broken patches of colour. This is what the designers of the windows in the choir have done, for they have seen that by that means, and not by the representation of architectural forms, they obtain the best contrast with the real architectural forms of the building. At their best, the windows of the choir remind one of patches of coloured sunlight on running water. It is true that these windows are really filled with pictures, but these pictures are only an excuse and a stimulus for the inventions in pure colour of the designer. Without them his work might seem merely kaleidoscopic. It is his great merit that he has never allowed his representation of actual things to interfere with his decorative purpose. [Illustration: Compartment of Ancient Choir Stalls.]