Oh, he understood, all right. He knew what tugged at his son's heels, he knew the consuming thrill, the insatiable hunger to reach higher and higher, to seek out unknown places. He knew the wonder of stepping on another land, an alien land, the thrill of watching two moons creep softly over a reddish horizon. He knew the deep, rich thrill of pushing the frontier outward until the sun winked coldly like another star. Memories flooded his mind, and he remembered too well the insistent tug of the wanderlust at his heels, the call of the open road, the call of space. And he knew that, try as he would, no Earth-bound answer would ever drive it away-- Yes, he understood. But deep in his heart he felt the coldness, the pain and agony, the sense of bitter loss. He was one of the lucky. He had come back. Tad would never come back. The odds were too great, there were too few of the lucky. And it was better _not_ to be one of the lucky, better to die out there, forgotten, unmourned. * * * * * Maybe he should have told the boy while he was young, tried to teach him, to make him understand. Perhaps he'd been wrong to conceal it all these years, to lie to Tad, to make Florence conceal, too. Perhaps Tad should have been told--but even knowing that someday the wanderlust would come, he knew he couldn't have told him. Better to conceal, to wait for the contempt, wait to hear the words, short, bitter words: "_How could you ever understand? You've never been there_--" George felt the perspiration trickle down his neck. How could he explain the things he hardly dared think about himself? The fear, the bitterness, the horror? Tad would be sleeping now, peacefully, in his room, his bag half packed on the dresser, dreaming dreams of wonder in his sleep, and never dreaming for an instant of the terror, the pain--never knowing how hard a taskmaster the wanderlust could be, what terrible fees it could exact. He knew he couldn't fight it. He had known since Tad was born that it would be useless. For the young saw only what they wanted to see.