"I think so."
"You can't, probably. How can anyone go where no one has been before? There's nothing. It just isn't. It's only a door, Rikud."
"No—" Rikud began, but the words faded off into a sharp intake of breath. Rikud had turned the knob and pushed. The door opened silently, and Crifer said, "Doors are variable, too, I think."
Rikud saw a small room, perhaps half a dozen paces across, at the other end of which was another door, just like the first. Halfway across, Rikud heard a voice not unlike that of the reading machine.
He missed the beginning, but then:
—therefore, permit no unauthorized persons to go through this door. The machinery in the next room is your protection against the rigors of space. A thousand years from now, journey's end, you may have discarded it for something better—who knows? But if you have not, then here is your protection. As nearly as possible, this ship is a perfect, self-sustaining world. It is more than that: it is human-sustaining as well. Try to hurt yourself and the ship will not permit it—within limits, of course. But you can damage the ship, and to avoid any possibility of that, no unauthorized persons are to be permitted through this door—
Rikud gave the voice up as hopeless. There were too many confusing words. What in the world was an unauthorized person? More interesting than that, however, was the second door. Would it lead to another voice? Rikud hoped that it wouldn't.
When he opened the door a strange new noise filled his ears, a gentle humming, punctuated by a throb-throb-throb which sounded not unlike the booming of the engines last week, except that this new sound didn't blast nearly so loudly against his eardrums. And what met Rikud's eyes—he blinked and looked again, but it was still there—cogs and gears and wheels and nameless things all strange and beautiful because they shone with a luster unfamiliar to him.
"Odd," Rikud said aloud. Then he thought, "Now there's a good word, but no one quite seems to know its meaning."
Odder still was the third door. Rikud suddenly thought there might exist an endless succession of them, especially when the third one opened on a bare tunnel which led to yet another door.