 One of the main causes of trepidation as Riduk prepares to enter the garden is
When nobody aboard ship remembers where it's going, how can they tell when it has arrived? But ever since the engines somewhere in the rear of the world had changed their tone, from the steady whining Rikud had heard all twenty-five years of his life, to the sullen roar that came to his ears now, the feelings had grown. Rikud knew that something which he could not explain had entered the elder man's head for a moment, but it had departed almost before Chuls knew of its existence. But something soft had cushioned the impact—something which had come into being just for the moment and then abruptly passed into non-being again, something which was as impalpable as air. The people had decided that they did not know where they were going, or why, and that it was unfair that the elders alone had this authority. He could see the look of easy contentment on Chuls' face as the rays fanned down upon him, bathing his old body in a forgotten magic which, many generations before Rikud's time, had negated the necessity for a knowledge of medicine. Rikud often thought of his own death, still seventy-five years in the future, not without a sense of alarm. "Yes?" Almost no one read any more, and the library was heavy with the smell of dust. "Astronomy says some stars are variable," Crifer offered, but Rikud knew his lame-footed companion understood the word no better than he did. Over on Rikud's right, Chuls began to dress. The view had changed, and the strangeness of it made Rikud's pulses leap with excitement. Presently Rikud became aware that his eyes were not tearing any longer, and he turned to look at the viewport. Rikud turned again to the port, where he could see nothing but an obscuring cloud of white vapor, murky, swirling, more confusing than ever. The gardens, moreover, did not jump and dance before his eyes the way the viewport gardens did. For a whole week that view did not change, and Rikud had come to accept it as fact. And when Chuls looked away in disinterest, Rikud became angry. If he, Rikud, walked from one part of the world to another, it was with a purpose—to eat, or to sleep, or perhaps to bathe in the health-rays. Now if the world had walked from—somewhere, through the vast star-speckled darkness and to the great garden outside, this also was purposeful.
 is its vast endlessness.
 nothing.  Riduk is ready to go.  is its vast endlessness.  Riduk is fearful that his shipmates will want to go with him, and he wants the garden and its beauty for himself.  that Riduk is fearful he will get caught and punished for attempting to leave.