Christianity spread rapidly, from its source in Palestine, into Syria, Asia Minor, Egypt, and Greece, and soon penetrated into Rome. And it is precisely in the Catacombs of Rome that we find to-day the most important remains of early Christian Art.
In the immense capital of the empire, among its countless inhabitants, Christianity had at once found disciples, and, as we know, not alone amongst the lower classes of society, but also amongst the highest. The rich received their new brethren into their own houses for religious gatherings and ceremonies, and allowed the dead to be placed in their own family sepulchres.
It was in the tablinum or reception-hall that the priest, assistants, and flock held their meetings and celebrated their ritual. The eucharistic tripod filled the place of the altar of the Lares in the adjoining peristyle; the catechumens and penitents remained in the atrium. Several of these houses eventually became regular churches, and kept the name of their owner, as for example the church that was founded in the house of Pudens (a Roman Senator baptised by the Apostles), and called Basilica Pudenziana, and later, Santa Pudenziana. A few traces of this house are still to be seen in the church itself, but of the others that were likewise transformed into churches, and of the oratories and churches before the time of Constantine, no trace is left. On the other hand, some of the houses consecrated by martyrdom are still preserved, above or within which arose, at a later date, oratories and churches, such as that of S. Cecilia in Trastevere and SS. Giovanni e Paolo on the Cúlian Hill.
In a very short while the tombs of the patricians could no longer hold the bodies of the Christians, who were rapidly increasing in number; the rich, therefore, not only enlarged their own family sepulchres for this purpose, but also gave land, wherein Christian cemeteries might be dug, which was eagerly appropriated by the various Christian religious communities that had arisen in the interval, and finally by the Ecclesia or greater community.
The associations or colleges, and in time also the burial societies, were recognised by the laws of Rome; rights of ownership and the inviolability of the sepulchres were ensured. The Christians were thus enabled openly to excavate and visit their cemeteries, and even went so far as to erect at the entrance buildings where they might meet and hold their love feasts.
Like the Pagan cemeteries, these were all situated outside Rome along the main roads: Via Ostiensis, Appia, Portuensis, Ardeatina, Salaria, etc. The most ancient is on the Via Ardeatina, at the point where it branches from the Via Appia, and was known as Domitilla, after Flavia Domitilla, niece of the Emperor Vespasian, the proprietor of the ground in which it was excavated. On the Via Appia were the cemeteries of Praetextatus and of Lucina, also named after the respective donors of the land. The last named, which is extremely spacious, belonged to the Ecclesia. More spacious still, and also belonging to the Ecclesia and situated on the Via Appia, was the cemetery of Callixtus, a priest who lived in the time of the Emperor Septimius Severus, and who was charged with administering its affairs till 217, when he became Pope.
The name of these Christian necropoli was Cúmeterium, place of sleep or resting-place. The name Catacomba is of much later date, when they were no longer in use. The only cúmeterium that remained open, and that was visited by pilgrims, was on the Via Appia (near the place where stands now the little church of Saint Sebastian), and close to some sandstone caves called Catacumbae. The guidebooks noted that this cemetery, was ad catacumbas. The pilgrims were in the habit of saying, "We are going ad catacumbas"; and thus the name came into use and was finally applied to the first Christian cemeteries which had been dug underground.
The Christian catacomb, to adopt the customary nomenclature, was excavated in the tufaceous subsoil on the outskirts of Rome, in imitation of the pagan columbaria, as being simple, not very costly, and capable of receiving a large number of bodies. But, since the Christian rite prescribed interment, openings in the walls, or loculi, were substituted for the niches which held the cinerary urns. These loculi were parallel to the walls, but were deep enough to hold two or even three bodies; the rooms were few in number and very small, mere cubicles; and since much space was needed for burying so great a number of dead, and since it must be done at the least possible expense, ambulatories or very narrow corridors were preferred, very lofty and extremely close together.
Square cubicles with intersecting vault or a depressed cupola were generally reserved for families of good standing, for Popes, 1 priests, and martyrs, whose bodies were placed in sarcophagi made of stone, or hewn out of the tufa and covered with a large stone; above this was left a deep niche known as an arcosolium, and beside it was hewn, in the tufa itself, one or sometimes two seats for the bishop and the priest. Mass was celebrated on the stone which formed the lid of the sarcophagus: thus it served as the mensa of the Christian altar. When, by dint of excavating corridors and cubicles, the stratum adapted to excavation was used up, a well was sunk till another suitable stratum was reached for excavating a new floor of corridors and cubicles, after which the process was repeated. In this way there came to be several catacombs with three, and one or two even with five floors, communicating by means of narrow flights of stairs. The Catacomb of S. Callixtus still has four floors which it is possible to visit, and another at a depth of 25 metres below the surface.
As there had been no mystery about excavating the Catacombs, so there was none in opening them; the Christians had free access to them, even in times of persecution, in order that they might accompany the bodies of friends and martyrs and visit their honoured tombs, especially on the anniversaries of their death, known as the natalia. This went on down to the time of the Emperor Valerian, who was the first to forbid meetings to be held in the oratories, or even in the chambers of the agape at the entrance to the Catacombs. Cubicles were then set apart inside the Catacombs for meetings and religious functions, as for example in the Catacomb of Priscilla and in that of Ostia on the Via Nomentana. Diocletian in his turn ordered the Catacombs themselves to be closed, and the Christians very soon began to wall up the public entrances and to open others, which were disguised by mazes of tunnels.
Notwithstanding the darkness pervading these innumerable recesses in the Catacombs, they nevertheless received pictorial decoration, consisting of a continuous series of fresco-paintings which proreeds uninterruptedly from the first century to the fifth, and continues to afford a few isolated examples right down to the ninth century.
The oldest paintings go back, then, to the second half and end of the first century; they are to be found in the Catacombs of Domitilla and Priscilla, and are few in number.
They continue to increase during the second century, become very numerous in the third, and in the fourth almost universal. Immediately after the beginning of the fifth century, i.e. after 410, they suddenly cease almost entirely, that is to say when the Catacombs were no longer used as burialplaces, but were reserved for the cult of the martyrs, in whose tombs alone it was that a few paintings were added from time to time.
As we have already foreseen in talking of Roman painting, they are all artistically works of a very humble order, and with the decline and fall of art in Rome they also become more and more decadent. Yet they are of supreme importance in the history of art. We see in them "the beginnings of the new art engrafted on the old" ( Wilpert).
At first they consisted only of simple ornamentation, like that in the houses and sepulchres: the ceilings were adorned with trellises, vine-tendrils, compartments decorated with foliage and flowers, birds, vases, masks, etc. Some of these motives are graceful and elegant.
Later the choice of ornamental motives was confined more especially to such as had symbolic significance: vine-tendrils, small figures or heads representing the four seasons; and they further began to depict on the walls some pagan subject which might be symbolically adapted to Christian ideas, such as the shepherd with the lamb, who might symbolise the Good Shepherd or even certain Christian subjects, Noah in the Ark, Daniel in the Lions' Den. But the style was of course still pagan, that is to say Graeco - Roman: Christianity could not all at once create a new art, nor indeed did it at that time aspire to do so. The subjects were likewise pagan and hence Graeco-Roman in their details; but in those chosen and in the symbols added we can already discern a distinct significance.
The symbolic character of these paintings and the frequent recurrence of certain symbols, both in the paintings or on the stones and on the layers of masonry closing the tombs or loculi, or even on the lamps of terra-cotta and bronze, as, for instance, the dove, the peacock, the anchor, etc., etc., betray their Oriental origin. Christianity was, in fact born in the East, and when it penetrated to Rome took with it Eastern thoughts and feelings, and necessarily Eastern imagery; moreover, it was in the Greek tongue that the story of the life and teaching of Christ was spread abroad, for Greek was the universal language of the Graeco-Oriental world, which was much vaster and more thickly populated than the Roman world of the West. But the types, subjects, and symbols of the first paintings in the Catacombs, even though they wear a GraecoRoman dress, are inspired by Eastern ideas. These subjects and symbols translated into the medium of figures became, as Bertaux notes, words in the "international language of Christianity."