"The truth is simple," said the man called Dzell. "We have told it before, but no one believed, and it has not seemed wise to support our facts. We, Dzorr and I, with our companions Dzinn and Dzett, are explorers." John Drinkard slapped his hand against the boulder beside him and seemed reassured by its solidity. He shook his head to clear it. "I don't get it," he objected. "Chuck and I could call ourselves explorers, too, if rambling around the mountains every chance we get falls under that heading." "We do not explore the mountains," said Dzell. "Here we rest and allow ourselves to behave normally. We explore in the towns and in the cities, where people gather. It is strenuous," he added, with a sound almost like a sigh. "We cannot tolerate it for long. Then we must go into seclusion and renew ourselves." Keen interest was replacing puzzlement in both Evers and Drinkard. They smiled now and Chuck said: "I know what you mean. Ten days in Denver--a fine town, mind you--and I feel like I'd been staked with a short rope." "You do not exactly know what I mean," said Dzell. "Your problems are simply matters of preference. Ours are physiological. We cannot long maintain metabolic balance in the company of people. Thus, Dzinn and Dzett are now in the world you inhabit. When they must rest, then our turn comes." * * * * * Dzell had gathered a pile of small flat stones and he sat sorting them with his gauntleted fingers. They were simply flakes of weathering gneiss, fire- and pressure-derived from some granite as ancient as the range. Neither man noticed the idle movements until Dzell raised a piece to his mouth and bit into it with a grinding sound, like a man cracking nuts. His teeth were large and square, and they had a metallic gleam. They made short work of the gneiss. Dzell flexed his fingers, selected another piece of the rock. "Among people," he observed, "this would be conspicuous. You are not adapted to get oxygen from quartz. We are." "You make Houdini look like a piker," big John told him admiringly. "I admit that's tougher cereal than I'd want to try. But the point of the gag still escapes me." "I am aware of that," said the strange man. "You cannot comprehend because your mind is shackled. Yet it must be evident that we are not too much alike." He rose to his feet. "There is the matter of the body glow. I can control my body temperature, raising and lowering it as I choose. The greatest difficulty when I am among people is to keep it down to human body heat. Normally it is very much higher than yours. And when, due to exercise and metabolic speed-up, excess energy is accumulated, it is satisfying to us to radiate it. You get the same release by deep sighs, by long breaths, by stretching your limbs. Unfortunately, when we radiate rapidly in air, we glow. It has made us conspicuous."