 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? Every day for a week now, Rikud had come to the viewport to watch the great changeless sweep of space. 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. But it came again, and each time it left him with a feeling he could not explain. 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. There was a strange thought, and Rikud's brain whirled once more down the tortuous course of half-formed questions and unsatisfactory answers. 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. There had been a revolt—again a term without any real meaning, a term that could have no reality outside of the reading machine—and the elders were overthrown. 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. Much of this Rikud could not understand, but he knew enough to realize that the reading machine had sided with the people against the elders, and it said the people had won. 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. But when, in another ten years, Chuls would perish of old age, the rays would no longer suffice. 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. This was a new thought to Rikud, and he propped his head up on one elbow. "You know," Rikud said, sitting up now, "the stars in the viewport are changing." "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.
 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.