"Why not?" said the Philosophical Inventor.
"It's against reason," said Filby.
"What reason?" said the Philosophical Inventor.
"You can show black is white by argument," said Filby, "but you will never convince me."
"Possibly not," said the Philosophical Inventor. "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—— "
"To travel through Time!" said the Very Young Man.
"That shall travel indifferently in any direction of Space and Time, as the driver determines."
Filby contented himself with laughter.
"It would be remarkably convenient," the Psychologist suggested. "One might travel back and witness the battle of Hastings."
"Don't you think you would at-
