Few ancient monuments that have come to light of recent years have aroused so lively an interest amongst scholars or so widespread a curiosity in the general public as the subterranean building of basilican plan discovered in 1917 as if by chance near the Porta Maggiore in Rome. Its situation at a depth of 50 feet below the present level of the soil, the curious mode of its construction, the secrecy of its approach, the mystical character of its decoration led to the theory, put forward almost from the first, that this was probably the secret meeting-place of some religious pagan fraternity. Especially significant in this connexion are the symbolic and eschatological subjects of the stuccoes: the figures of Eros holding torches or playing with a butterfly, the scenes of rape and of liberation, the Victories carrying wreaths belong to the now well-known cycle of subjects that symbolise the aspiration of the soul towards the divine, her liberation from earthly ties and her final flight towards the celestial spheres. In the same way, the long series of reliefs representing sacred enclosures which completely surround the lower part of the walls; the scenes of preparation and of ritual discipline; those of initiation to the mysteries; the indications of a purgatorial Katharsis; the grand apocalyptic scene of the apse; the figures interpreted as Orantes or personified prayers; even the candelabra and other sacred furniture, recall rites by means of which the ancient devotees of the basilica might be initiated while still in this life to the bliss of the next. The subjects considered individually offer nothing either strange or unique, but what strikes our imagination and must certainly have struck that of any one who entered the basilica in antiquity, is to find so large a number of these subjects (their number is, I believe, about 117) so linked together as to cover the whole building with a perfectly logical and homogeneous decoration.