Richard Phené Spiers

“ The early Renaissance architects in France in some cases, and notably in the apsidal chapels of St Pierre at Caen (1520) , seemed to feel that the stained glass was too much cut up by the tracery and mullions, and omitted them altogether, trusting to the iron stanchions and cross-bars to carry their glass, so that a return was made to the simple semicircular-headed window of Roman times, retaining only the mouldings of the late Flamboyant period for the jambs and arch-moulds. ”

“ In France, square-headed windows were almost always employed, owing to the earlier introduction there of the Renaissance style, when the decoration of the mullions, generally consisting of classic pilasters, required some kind of architrave, frieze and cornice, to render the order complete ”

“ In the later styles the windows assume much greater importance, and in Gothic cathedrals almost govern the whole design. Already, however, in the earliest Byzantine church, Sta Sophia at Constantinople, the windows constituted one of the chief features of the church; the forty windows round the base of the cupola giving an exceptional lightness to the structure; besides, there are windows in the larger and smaller apses and the north and south walls. The windows in the latter, which are of great size, are subdivided by marble mullions with pierced lattices between of transparent marbles. ”