But even if he could accept the psychologist's authority for the cumulative effect of a gravity system, he could not understand the unspoken warning he felt underlying all that the man said. "Of course it has changed," Craig was protesting. "Anyway, I never really knew very much about Terra. So what? I know it won't be as it was in tapezines either." "Yet you are so completely sure you will want to live out your life there, that you are willing to give up space service for it." "We've gone through this time and time again," Craig said wearily. "I gave you my reasons for quitting space. We analyzed them. You agreed that you could not decide that for me and that my decision is logical. You tell me spacemen don't settle down on Terra. Yet you won't--or can't--tell me why. I've got a damned good job there--" "You may find that 'damned good jobs' become boring." "So I'll transfer. I don't know what you're trying to get at, Captain, but you're not talking me out of going back. If the service needs men so badly, let them get somebody else. I've put in _my_ time." "Do you really think that's my reason?" "Sure. What else can it be?" "Mr. Craig," the psychologist said slowly, "you have my authorization for you to return to Terra as a private citizen of that planet. You will be given a very liberal supply of PON--which you will definitely need. Good luck. You'll need that too." * * * * * On the eighth day, two attendants, who showed the effects of massive doses of PON to protect themselves from the centrifugal force, had to carry a man out of the tank. Many others asked to be removed, begged to be allowed to withdraw their resignations. "The twelfth day is the worst," a grizzled spaceman told Craig. "That's when the best of 'em want out." Craig clenched the iron rung of his bed and struggled to bring the old man's face into focus. "How ... how do they know when you ought ... to come out?" he asked between waves of nausea. "Blood pressure. They get you just before you go into shock." "How can they tell?" Craig fought down his growing panic. "I can't." "That strap around your belly. You mean you ain't noticed it?" "Haven't noticed much of anything." "Well, it's keyed to give them some kind of signal." The old man lapsed into silence. Craig wished him to continue. He desperately wanted something to distract his mind from the ghastly conditioning process. Slowly at first, the lines formed by seams in the metal ceiling began to bend. Here it came again! "Old man!" shouted Craig. "Yeah, son. They've dropped it down a notch." "Dropped ... it ... down?" "Maybe that ain't scientific, but it's the way I always think of it." "Can't they ... drop it down continuously?" "They tried that a few times--once when I was aboard. You wouldn't like it, kid. You wouldn't like it at all." "How ... many times ... do they drop it?" "Four times during the day, three at night. Twenty days."