As we uttered this name Tizoc turned towards us quickly, and with a startled, troubled look upon his face. "They are not of our race," he said, as though speaking his thoughts aloud; "yet the sacred name, that among us only a few know, is known to them!" and the troubled look upon his face deepened as we went onward.
The way by which we descended was a narrow road carried zigzag down the cliff--for the pass by which we had entered the valley was fully six hundred feet above the level of the lake--and at short intervals along its course this road was defended by walls of very solid masonry, pierced with openings so narrow that only one man at a time could pass through them. That the walls were for defence was shown by the piles of metal bars on the inner side of each opening--the side towards the mountain--so arranged that in a moment they could be slipped into sockets in the stone-work, thus closing effectually the way.
Perceiving that we regarded with surprise this curious system of fortification, Tizoc explained: "These are the barriers set up against the Tlahuicos, who, heeding not the order given of old by our lord Chaltzantzin, have striven many times to break forth from the valley--for among these men there are many of perverse natures and evil minds."
In _tlahuico_ I recognized a Nahua word that means "men turned towards the earth," but what its meaning might be in the sense in which Tizoc employed it I did not know. I should have asked for further explanation--for the manner of this man was so frank and so friendly that it invited a cordial familiarity--but as I was about to speak we passed through the narrow opening in a wall of unusual height and strength, and so came into a charming garden, in the midst of which stood a large house well built of stone. For the making of this garden a natural nook on the side of the mountain had been enlarged by filling in along its outer edge against a great retaining-wall, built up from a depth of a hundred feet from the slope below; and on the farther side of the plateau thus created, where the path down into the valley went on again, were heavy defensive walls. Near this exit, also, was a long low building that I took to be a guard-house.