The shades, those sombre hatchers of primitive Christianity, only awaited an opportunity to bring about an explosion under the Caesars and to inundate the human race with light. For in the sacred shadows there lies latent light. Volcanoes are full of a shadow that is capable of flashing forth. Every form begins by being night. The catacombs, in which the first mass was said, were not alone the cellar of Rome, they were the vaults of the world.