In each period these are distinct in design from all that went before or came after, and thus to catch the spirit of any one Gothic period aright, it is not enough to fix the general shapes of the arches and proportions of the piers but every feature, every moulding, and every ornament must be wrought in the true spirit of the work, or the result will be marred. _Stained Glass._ Ornamental materials and every sort of decorative art, such as mosaic, enamel, metal work and inlays, were freely employed to add beauty in appropriate positions; but there was one ornament, the crowning invention of the Gothic artists, which largely influenced the design of the finest buildings, and which reflected a glory on them such as nothing else can approach: this was stained glass. So much of the old glass has perished, and so little modern glass is even passable, that this praise may seem overcharged to those who have never seen any of the best specimens still left. We have in the choir at Canterbury a remnant of the finest sort of glass which England possesses. Some good fragments remain at Westminster, though not very many; but to judge of the effect of glass at its best, the student should visit La Sainte Chapelle at Paris, or the Cathedrals of Chartres, Le Mans, Bourges, or Rheims, and he will find in these buildings effects in colour which are nothing less than gorgeous in their brilliancy, richness, and harmony. [Illustration: FIG. 29.--STAINED GLASS WINDOW FROM CHARTRES CATHEDRAL.] The peculiar excellence of stained glass as compared with every other sort of decoration, is that it is luminous. To some extent fresco-painting may claim a sort of brightness; mosaic when executed in polished materials possesses brilliancy; but in stained glass the light which comes streaming in through the window itself gives radiance, while the quality of the glass determines the colour, and thus we obtain a glowing, lustre of colour which can only be compared to the beauty of gems. In order properly to fill their place as decorations, stained-glass windows must be something quite different from transparent pictures, and the scenes they represent must not detach themselves too violently from the general ground. The most perfect effect is produced by such windows as those at Canterbury or Chartres (Fig. 29), which recall a cluster of jewels rather than a picture. _Coloured Decoration._ Colour was also freely introduced by the lavish employment of coloured materials where they were to be had, and by painting the interiors with bright pigments. We meet with traces of rich colour on many parts of ancient buildings, where we should hardly dare to put it now, and we cannot doubt that painted decoration was constantly made use of with the happiest effect. _Sculpture._ [Illustration: FIG. 30.--SCULPTURE FROM THE ENTRANCE TO THE CHAPTER HOUSE, WESTMINSTER ABBEY. (1250.)]