Wherever a sacred association had to be fixed, a cave was immediately selected or found as its home? In Europe the veneration of the martyrs became in the Middle Ages the leading prin ciple of Christian worship; and in many places the earth or rock about their tombs was re moved until the sarcophagus was exposed, and then a chapel, wholly or partially sub terranean, was built about it. The crypts of ancient churches owe their origin to this cus tom, and many old cathedrals and churches in Europe rest on such sites.
All these influences resulted in the hewing of early and mediaeval churches out of the massif of cliffs and hillsides. Egypt has sev eral rock-hewn temples of this kind; and they occur in Palestine, Crete, Spain, France, Eng land and elsewhere. How elaborate many of them are may be illustrated by a single example, that of Saint Emilion, in the valley of the Dordogne River, France, where, in the middle of the 8th century, a hermit named Emilian lived in a small cave, still to be seen. He be came celebrated as a teacher, and finally a monastery and gradually a town grew up in the valley below. Beside the town rises an abrupt mass of rock, hollowed out into a stately church. Its ground-plan measures 120 by 60 feet. The front contains a vestibule, 21 feet high, with doors and windows pierced in the face of the rock. The three lower windows are of the flamboyant order, the upper three (clearstory) are round; the principal doorway through the rock-wall is richly sculptured.
The body of the church stands parallel with the face of the cliff, and is 95 feet long and 60 feet high. It consists of a nave and side aisles, all excavated out of the living rock, the pillars left square, the ceiling accurately vaulted, and the whole dimly lighted by the vestibule windows. The pillars are plain. and without capitals, but quaint large figures are carved on the walls and at the rear of the choir.
Coincident with these mediaeval churches several famous monasteries began as cave hermitages, and were enlarged into series of halls and cells cut out of solid rock. These were in some cases occupied for hundreds of years, supplemented by, or giving place to, buildings erected near them. Examples of such cave-monasteries of old times are to be found even in England.
Bibliography.— The most complete sum mary of information relating to modern cave dwellers is to be found in Baring-Gould's 'Cliff-Castles and Cave-Dwellings of Europe) (Philadelphia 1911) ; for local particulars else where, consult geographical treatises, such as the 'Universal Geography) of Reclus; books by explorers and travelers; the publications of archaeological institutes; scientific periodicals, and local histories—mostly in foreign lan guages.