Reaching down from the passage into the abyss was the head of a steep flight of steps—small, numerous steps like those of the black passages I had traversed—but after a few feet the glowing vapors concealed everything. Swung back open against the left-hand wall of the passage was a massive door of brass, incredibly thick and decorated with fantastic bas-reliefs, which could if closed shut the whole inner world of light away from the vaults and passages of rock. I looked at the steps, and for the nonce dared not try them. I touched the open brass door, and could not move it. Then I sank prone to the stone floor, my mind aflame with prodigious reflections which not even a death-like exhaustion could banish.