The cathedral is the work of many hands. Hardly one of its long line of bishops but has left his mark upon it. But that it is an architectural masterpiece is due in the first place to the genius of one man, and in the second place to the wisdom of his successors in faithfully carrying out his original design. The cathedral stands on the site of a Saxon church, of which no trace remains; and of the Norman edifice which succeeded it little is left but the two transeptal towers. These towers, the northern of which has been much altered, and now has strongly-marked Perpendicular characters, were built by Bishop Warelwast (1107-1136), the son of William the Conqueror's sister; and Bishop Marshall (1194-1206), brother of that Earl of Pembroke who helped Henry II in the conquest of Ireland, finished the building in the Norman style. But it was Bishop Quivil (1280-1291) who planned the reconstruction of the whole cathedral in the Decorated style, with the exception of the towers, and himself began the transformation, rebuilding the transepts, the Lady-chapel, and part of the nave. And although the work extended over more than a hundred years after Quivil's time, and was continued far into the Perpendicular period, the architecture was not altered, and there are few features in the building which are not in keeping with the bishop's first design. The magnificent Perpendicular eastern window is filled with beautiful glass of the previous period, and it is believed that its tracery also was originally of the Decorated style. [Illustration: The Nave, Exeter Cathedral] Of the bishops who succeeded Quivil, Stapledon (1308-1326), a statesman as well as a prelate and an architect, murdered in Cheapside by ruffian partisans of the She-Wolf of France, carried out some of the finest work in the building, including the rood-screen, the episcopal throne, and the stone sedilia. Last of the great builders was Bishop Grandisson (1327-1369), who, in his long tenure of the see, completed and finally consecrated the cathedral, to which, however, some details were added by those who followed him. Bishop Brantyngham (1370-1394), for instance, finished the west front, the great east window, and the cloisters--destroyed by the Puritans and only recently rebuilt. There have been two main restorations of the cathedral; one in 1662, and one between 1870 and 1877, when the reredos and other features were added. The chapter-house, which is an exception in style to the rest of the building, its lower part being Early English, and its upper part Perpendicular, contains part of the cathedral library. The rest of the 15,000 volumes of books, together with some very valuable manuscripts, including the Exeter Domesday Book, Leofric's Book of Saxon Poetry, and the original charter signed by Edward the Confessor, Earl Godwin, Harold and Tostig, authorising the removal of the see from Crediton to Exeter are preserved in the Chapter Library.