"The pointed Gothic style which had its origin in the north of France about the middle of the twelfth century appeared in England about 1170, but can scarcely be said to have reached Scotland till after the close of the twelfth century.... The pointed arch, for example, although generally adopted, did not entirely displace, as it had done in the south, the round form of the Normans, a feature which, especially in doorways, continued to be employed not only in the thirteenth century, but throughout the whole course of Gothic art in Scotland. In other respects the thirteenth century style in this country corresponds very closely with that of England. Its features are however, generally speaking, plainer and the structures are smaller."[16] "This new departure sprung from the necessity which arose for the invention of an elastic system of vaulting which should admit of all the arches, forming vaults over spaces of any form or plan, being carried to the same height at the ridge. This requirement led to the introduction of the pointed arch in the vaulting, and from that departure it soon spread to all the other arched features of the architecture."[17] Architecture, which had hitherto been confined to the monasteries, was now undertaken by laymen, and while the great monasteries were either rebuilt or founded, the cathedrals mostly belong to this period. To these attention was chiefly devoted, and the number of parish churches constructed was comparatively small. This partly arose from the large number of parish churches built during the Norman period. In Scotland the cathedrals of St. Andrews, Dunblane, Glasgow (the choir and crypt), Elgin, Brechin, Dunkeld, Caithness, the choir of St. Magnus in Orkney and Galloway belong in whole or in part to this epoch.[18] 4. SCOTTISH MIDDLE POINTED OR DECORATED PERIOD