 What is not a theme explored in this story?
The Sense of Wonder By MILTON LESSER Illustrated by HARRY ROSENBAUM [Transcriber's Note: This etext was produced from Galaxy Science Fiction September 1951. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] 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. And, because he had realized this odd difference in himself, he kept it locked up inside him. The stars—it was a meaningless concept to Rikud, but that was what everyone called the bright pinpoints of light on the black backdrop in the viewport—were not apparent in the speckled profusion Rikud had always known. Instead, there was more of the blackness, and one very bright star set apart by itself in the middle of the viewport. But it came again, and each time it left him with a feeling he could not explain. Why should he think he was thinking such thoughts, when it always embroiled him in a hopeless, infinite confusion that left him with a headache? I saw you here and knew it was your time, too...." 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. Now why shouldn't a man be permitted to do what he wanted, when he wanted to do it? 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. Rikud had been stopped in this action, although there was no real authority to stop him.
 Equality must be realized.
 Change is necessary and inevitable for survival.  Fear is a powerful motivator.  Perception can often be all-encompassing.  Equality must be realized.