 What is the unspoken warning of the psychologist?
Flight Officer Robert Craig surrendered the tube containing his service record tapes and stood waiting while the bored process clerk examined the seal. "No specific destination," supplied the man as he punched a key on a small instrument, "Air-lock ahead and to your right. "Place your clothing in the receptacle provided and assume a stationary position on the raised podium in the center of the lock." "Insert your right arm into the instrument on the central table," commanded the same voice he had heard before. "Mr. Craig, I suppose you've guessed that the next step in our little torture system here is psych." It helps suppress certain physiological reactions to an entirely new set of conditions. They play an important part in our awareness of balance. During the days that followed, the psychologist seemed to Craig to become progressively more didactic. He had been on Einstein IV, the planet of eight moons, and had felt the pulse of all eight of the satellites at once that no PON could completely nullify. 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. "Mr. Craig," the psychologist said slowly, "you have my authorization for you to return to Terra as a private citizen of that planet. 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. "How ... how do they know when you ought ... to come out?" "Can't they ... drop it down continuously?" "How ... many times ... do they drop it?" Either that or they had begun to produce ultra-sonic waves. The huge headquarters base centrifuge aboard the man-made satellite had gradually caused their bodies to respond once more to a single source of pull. They were now ready to become inhabitants of planets again, instead of free-falling ships. On the eighteenth day, automatic machinery freed them from their imprisoning cots. Then they again began taking paraoxylnebutal in preparation for the free-fall flight to Terra. Only one of the score of men in the centrifuge tank remained voluntarily in his cot. "Not to Chociante, if that's what you mean.
 The culture on Terra is radically different from the culture in space.
 Even good jobs get boring on Terra.  Private citizens do not enjoy the same rights as spacemen.  The culture on Terra is radically different from the culture in space.  The gravity on Terra could make a spaceman feel sick all the time.