Other minor works were added during the fourteenth century, but to few of these can any exact dates be assigned. The parapets to the north and south wall of the nave, the choir, and lady-chapel, and the painted oak choir-stalls were some of those additions. In the fourteenth century we meet many changes in the treatment of the windows. They became larger; they were themselves very treasuries of design, and this not only for the stonework of their tracery, but also for the very beautiful glass with which they had been filled. Their outer arches are more varied in shape, more rich in moulded detail, and the entire character of the curves of the moulded forms had been developed and made more delicate than the stronger and deeper-cut types from which they were derived. Two causes had apparently urged the builders to exert their capacities and apply their increasing technical skill to compass the aims proposed to them. The small windows, the use of which had so long prevailed, did not admit sufficient light. In the more southern countries there was not the same reason for the change; but where light was less strong, less clear, less penetrating, it might not be spared. So though with their glass they were beautiful in themselves, many of these windows gave place to larger ones. But if the admission of more light was one reason for the change, there was another powerful inducement offered by the larger field that might be provided for the use of decorative colour, and they accepted the opportunity with alacrity--not as a mere chance for display only, but because, rather, they would be enabled to teach by the use of it.