"Since the beginning of time, little by little, stone by stone, have the therns been ever adding to the defences of their stronghold. A continuous line of impregnable fortifications circles the outer slopes of the Mountains of Otz.
"Within the temples that lie behind the ramparts a million fighting-men are ever ready. The courts and gardens are filled with slaves, with women and with children.
"None could go a stone's throw without detection."
"If there is no other way, Thuvia, why dwell upon the difficulties of this. We must face them."
"Can we not better make the attempt after dark?" asked Tars Tarkas. "There would seem to be no chance by day."
"There would be a little better chance by night, but even then the ramparts are well guarded; possibly better than by day. There are fewer abroad in the courts and gardens, though," said Thuvia.
"What is the hour?" I asked.
"It was midnight when you released me from my chains," said Thuvia. "Two hours later we reached the storeroom. There you slept for fourteen hours. It must now be nearly sundown again. Come, we will go to some nearby window in the cliff and make sure."
So saying, she led the way through winding corridors until at a sudden turn we came upon an opening which overlooked the Valley Dor.
At our right the sun was setting, a huge red orb, below the western range of Otz. A little below us stood the Holy Thern on watch upon his balcony. His scarlet robe of office was pulled tightly about him in anticipation of the cold that comes so suddenly with darkness as the sun sets. So rare is the atmosphere of Mars that it absorbs very little heat from the sun. During the daylight hours it is always extremely hot; at night it is intensely cold. Nor does the thin atmosphere refract the sun's rays or diffuse its light as upon Earth. There is no twilight on Mars. When the great orb of day disappears beneath the horizon the effect is precisely as that of the extinguishing of a single lamp within a chamber. From brilliant light you are plunged without warning into utter darkness. Then the moons come; the mysterious, magic moons of Mars, hurtling like monster meteors low across the face of the planet.