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--'

'To travel through Time!' exclaimed the Very Young Man.

'That shall travel indifferently in any direction of Space and Time,
as the driver determines.'

Filby contented himself with laughter.