In the early period of the art, beginning in the eleventh century and running parallel with the development of Pointed (commonly called Gothic) Architecture, only true stained glass was used. The use of enamel paints applied to the surface to produce a different color marks also the beginning of the decadence of the art; for the glory of true glass is in its jewel-like quality, its color being within itself and all absolutely translucent, while a painted glass will always be necessarily dull in comparison. The temptation to paint color upon the surface of glass is readily understood: it was an easier method, it promised wider scope, greater variety, in a word, the opportunity to make pictures somewhat as the painter may upon canvas. But glass is not canvas, and church windows are not to be pictures. Retribution has overtaken this work, and the latest and most ambitious more speedily than all; the enamel-painted glass has not stood the test of time, becoming muddy and perishing while the true ancient stained glass is still the joy and wonder of all who gaze upon it. For, as we have said, the glory of true stained glass is in its rich, jewel-like color. Its reds, which the makers called “ruby,” its blues which they called “sapphire,” with its “emerald” greens, its “gold” and its “pearl,” never entered the field to compete with the achievements of the painter’s brush; to compare the delight they afford the beholder with that derived from a painting would be in a sense as impossible as a comparison between the fragrance of a flower and the cadence of a song. The early makers of stained glass windows contended with great, to moderns they would be intolerable, limitations. They were almost absolutely restricted to the primary colors. They had not at first the art of blowing glass, but cast their pieces in small panes of at most four or five inches in diameter. The use of the diamond in cutting was not known till the sixteenth century. Hence their work was simply mosaic. For variety they depended upon an arrangement of geometrical patterns, or patterns of familiar architectural form and of common ecclesiastical symbols. To construct these they leaded together their pieces and bits of glass, elaborating their treatment as time went on, but always in the main upon the same lines.