§ 38.1. =The Catacombs.=--The Christian burying places were generally called κοιμητήρια, _Dormitoria_. They were laid out sometimes in the open fields (_Areæ_), sometimes, where the district was suitable for that, hewn out in the rock (κρύπται, crypts). This latter term was, by the middle of the 4th century, quite interchangeable with the name _Catacumbæ_, (κατὰ κύμβας=in the caves). The custom of laying the dead in natural or rock-hewn caves was familiar to pagan antiquity, especially in the East. But the recesses used for this purpose were only private or family vaults. Their growth into catacombs or subterranean necropolises for larger companies bound together by their one religion without distinctions of rank (Gal. iii. 28), first arose on Christian soil from a consciousness that their fellowship transcended death and the grave. For the accomplishment of this difficult and costly undertaking, Christian burial societies were formed after the pattern of similar institutions of paganism (§ 17, 3). Specially numerous and extensive necropolises have been found laid out in the immediate neighbourhood of Rome. But also in Malta, in Naples, Syracuse, Palermo, and other cities, this mode of sepulchre found favour. The Roman catacombs, of which in the hilly district round about the eternal city fifty-eight have been counted in fourteen different highways, are almost all laid out in the white porous tufa stone which is there so abundant, and useful neither for building nor for mortar. It is thus apparent that these are neither wrought-out quarries nor gravel pits (_Arenariæ_), but were set in order from the first as cemeteries. A few _Arenariæ_ may indeed have been used as catacombs, but then the sides with the burial niches consist of regularly built walls. The Roman Catacombs in the tufa stone form labyrinthine, twisting, steep galleries only 3 or 4 feet broad, with rectangular corners caused by countless intersections. Their perpendicular sides varied greatly in height and in them the burial niches, _Loculi_, were hewn out one above the other, and on the reception of the body were built up or hermetically sealed with a stone slab bearing an inscription and a Christian symbol. The wealthy laid their dead in costly marble sarcophagi or stone coffins ornamented with bas-reliefs. The walls too and the low-arched roofs were adorned with symbols and pictures of scripture scenes. From the principal passages many side paths branched off to so-called burial chambers, _Cubicula_, which were furnished with shafts opening up to the surface and affording air and light, _Luminaria_. In many of these chambers, sometimes even in the passages, instead of simple _Loculi_ we meet with the so-called _Arcosolium_ as the more usual form; one or more coffin-shaped grooves hewn out in the rocky wall are covered with an altar-shaped marble plate, and over this plate, _Mensa_, is a semicircular niche hewn out spreading over it in its whole extent. These chambers are often held in reverence as “catacomb churches,” but they are so small in size that they could only accommodate a very limited number, such as might gather perhaps at the commemoration of a martyr or the members of a single family. And even where two or three such chambers adjoin one another, connected together by doors and having a common lighting shaft, accommodating at furthest about twenty people, they could not be regarded as meeting-places for public congregations properly so called.--Where the deposit of tufa stone was sufficiently large, there were several stories (_Piani_), as many as four or five connected by stairs, laid out one above the other in galleries and chambers. According to _de Rossi’s_[103] moderate calculation there have been opened altogether up to this time so many passages in the catacombs that if they were put in a line they would form a street of 120 geographical miles. Their oldest inscriptions or epitaphs date from the first years of the second century. After the destruction of Rome by the hordes of Alaric in A.D. 410, the custom of burying in them almost entirely ceased. Thereafter they were used only as places of pilgrimage and spots where martyr’s relics were worshipped. From this time the most of the so-called _Graffiti_, _i.e._ scribblings of visitors on the walls, consisting of pious wishes and prayers, had their origin. The marauding expedition of the Longobard Aistulf into Roman territory in A.D. 756, in which even the catacombs were stripped of their treasures, led Pope Paul I. to transfer the relics of all notable martyrs to their Roman churches and cloisters.