During this long period--roughly from A.D. 1629 to about the middle of the nineteenth century, some 220 years--_the chief object and aim of Catacomb exploration were to procure relics_; when these were once carried away, no heed was paid to the crypts, or to the streets of graves. The records of the excavations kept were scanty and utterly insignificant, and each Catacomb from which the relics were taken was left in a state of utter ruin and deplorable confusion. The result of these searchings of 220 years has been that few discoveries were made of any real importance to early Christian history or archæology. At last De Rossi, in the middle years of the nineteenth century, took in hand seriously the study and scientific exploration of the vast Christian necropolis of Rome. De Rossi was the friend and pupil of Father Marchi, an indefatigable student of the Catacombs who was really impressed with the possibilities of a more careful exploration than had hitherto been undertaken. Marchi’s real title to honour will ever be that he imbued his pupil with a passionate love of the work to which he has devoted a long and strenuous life. The great City of the Dead, largely thanks to De Rossi’s lifelong labours, is to us something far more than a vast museum of inscriptions and memorials, the work of the Christian congregations in Rome during the first two and a half centuries which followed the preaching and martyrdom of SS. Peter and Paul. It is true that most important is the testimony of these precious relics to the earliest popular estimate of Christianity: we shall dwell later on the wonderful witness which the numberless inscriptions and strange emblems painted and graven on the tombs bear to the faith and belief of the early Church; but the eminent Roman scholar of whom we are speaking has taught us that there was more than even the witness of these precious inscriptions and emblems to be gathered from a patient study of the Catacomb secret. De Rossi believed, and the splendid results of his long toil have strikingly verified his belief, that amidst the ruined and desolated streets of graves the _historic crypts_ of the more famous and illustrious martyrs of Christ, of the men and women who during the first two centuries and a half through pain and agony passed to their rest and won their crowns, could be found and identified, and that thus a new and striking proof would be furnished of the truth of much of the martyr story of the early Church.