Several times we passed the entrances to other chambers similarly peopled, and twice again we were compelled to cross directly through them. In others were chained prisoners and beasts.
"Why is it that we see no therns?" I asked of Thuvia.
"They seldom traverse the underworld at night, for then it is that the great banths prowl the dim corridors seeking their prey. The therns fear the awful denizens of this cruel and hopeless world that they have fostered and allowed to grow beneath their feet. The prisoners even sometimes turn upon them and rend them. The thern can never tell from what dark shadow an assassin may spring upon his back.
"By day it is different. Then the corridors and chambers are filled with guards passing to and fro; slaves from the temples above come by hundreds to the granaries and storerooms. All is life then. You did not see it because I led you not in the beaten tracks, but through roundabout passages seldom used. Yet it is possible that we may meet a thern even yet. They do occasionally find it necessary to come here after the sun has set. Because of this I have moved with such great caution."
But we reached the upper galleries without detection and presently Thuvia halted us at the foot of a short, steep ascent.
"Above us," she said, "is a doorway which opens on to the inner gardens. I have brought you thus far. From here on for four miles to the outer ramparts our way will be beset by countless dangers. Guards patrol the courts, the temples, the gardens. Every inch of the ramparts themselves is beneath the eye of a sentry."
I could not understand the necessity for such an enormous force of armed men about a spot so surrounded by mystery and superstition that not a soul upon Barsoom would have dared to approach it even had they known its exact location. I questioned Thuvia, asking her what enemies the therns could fear in their impregnable fortress.
We had reached the doorway now and Thuvia was opening it.
"They fear the black pirates of Barsoom, O Prince," she said, "from whom may our first ancestors preserve us."
The door swung open; the smell of growing things greeted my nostrils; the cool night air blew against my cheek. The great banths sniffed the unfamiliar odours, and then with a rush they broke past us with low growls, swarming across the gardens beneath the lurid light of the nearer moon.