It is difficult to convey to a distant reader even a small share of the interest with which one sees on the spot evidences of the reality of the precautions with which, in those early centuries, the Christians of Rome were forced to guard themselves against a persecution which extended to their very burial-places,—­or even of the interest with which one walks through the unchanged paths dug out of the rock by this tenebrosa et lucifugax natio.  In the midst of the obscurity of history and the fog of fable, here is the solid earth giving evidence of truth.  Here one sees where, by the light of his dim candle, the solitary digger hollowed out the grave of one of the near followers of the apostles; and here one reads in hasty and ill-spelt inscriptions something of the affection and of the faith of those who buried their dead in the sepulchre dug in the rock.  The Christian Rome underground is a rebuke to the Papal Rome above it; and, from the worldly pomp, the tedious forms, the trickeries, the mistakes, the false claims and falser assertions, the empty architecture that reveals the infidelity of its builders, the gross materialism, and the crass superstition of the Roman Church, one turns with relief of heart and eyes to the poverty and bareness of the dark and narrow catacombs, and to the simple piety of the words found upon their graves.  In them is at once the exhibition and the promise of a purer Christianity.  In them, indeed, one may see only too plainly the evidences of ignorance, the beginnings of superstitions, the first, traces of the corruption of the truth, the proofs of false zeal and of foolish martyrdoms,—­but with these are also to be plainly seen the purity and the spirituality of elevated Christian faith.

In the service of the Roman Church used at the removal of the bodies of the holy martyrs from their graves in the catacombs is a prayer in which are the words,—­“Thou hast set the bodies of thy soldiers as guards around the walls of this thy beloved Jerusalem";—­and as one passes from catacomb to catacomb, it is, indeed, as if he passed from station to station of the encircling camp of the great army of the martyrs.  Leaving the burial-place of St. Agnes, we continue along the Nomentan Way to the seventh milestone from Rome.  Here the Campagna stretches on either side in broad, unsheltered sweeps.  Now and then a rough wall crosses the fields, marking the boundaries of one of the great farms into which the land is divided.  On the left stands a low farm-house, with its outlying buildings, and at a distance on each side the eye falls on low square brick towers of the Middle Ages, and on the ruinous heaps of more ancient tombs.  The Sabine mountains push their feet far down upon the plain, covered with a gray-green garment of olive-woods.  Few scenes in the Campagna are more striking, from the mingling of barrenness and beauty, from the absence of imposing monumental ruins and the presence of old associations.  The turf of the wide fields was cropped in the winter by the herds driven down at that season from the recesses of the Neapolitan mountains, and the irregular surface of the soil afforded no special indications of treasures buried beneath it.  But the Campagna is full of hidden graves and secreted buildings.