INTRODUCTION
directions of Space, but you cannot move about in Time."
"That is the germ of my great discovery. But you are wrong to say that we cannot move about in Time. For instance, if I am recalling an incident very vividly I go back to the instant of its occurrence: I become absent-minded, as you say. I jump back for a moment. Of course we have no means of staying back for any length of Time, any more than a savage or an animal has of staying six feet above the ground. But a civilized man is better off than the savage in this respect. He can go up against gravitation in a balloon, and why should he not hope that ultimately he may be able to stop or accelerate his drift along the Time-Dimension, or even turn about and travel the other way?"
"Oh, this," began Filby, "is all———"
"Why not?" said the Time Traveller.
"It's against reason," said Filby.
"What reason?" said the Time Traveller.
"You can show black is white by argument," said Filby, "but you will never convince me."
"Possibly not," said the Time Traveller. "But now you begin to see the object of my investigations into the geometry of Four Dimensions. Long ago I had a vague inkling of a machine———"
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