Few historical eras can be of greater interest than the days when Christian teaching began to spread in the Roman Empire and find followers in its capital. The revolution made by a new belief in the life and mores of Roman society, the features that were expressed in his understanding of Christian ideas and principles, all these are facts and phenomena of enormous importance, and the monuments that survived from this extraordinary era should be especially precious to us. Moreover, their number is very limited; monuments of literature are few; in the first centuries, Christians wrote little, and pagan historians, not predicting the great future of faith in the Savior, expressed themselves about this new, in their opinion, eastern sect with contemptuous brevity. Everything that both of them said about the first times of the spread of Christianity cannot expose to us the hidden fermentation caused by it in pagan society, nor imagine its secret course, its gradual development. We would not know this if the first Christians had not left behind the catacombs and the works of their art in them.