might know the
contents of Space and the laws of their arrangement and yet be unable
to see anything more than his fellows. It is a purely academic
knowledge. His mind knows it as the result of many deductions, but his
senses perceive nothing."

Leithen laughed. "Just what I said to Hollond. He asked the opinion
of my legal mind. I said I could not pronounce on his argument but
that I could point out that he had established no trait d'union between
the intellect which understood and the senses which perceived. It was
like a blind man with immense knowledge but no eyes, and therefore no
peg to hang his knowledge on and make it useful. He had not explained
his savage or his cat. 'Hang it, man,' I said, 'before you can
appreciate the existence of your Spacial forms you have to go through
elaborate experiments and deductions. You can't be doing that every
minute. Therefore you don't get any nearer to the USE of the sense you
say that man once possessed, though you can explain it a bit.'"

"What did he say?" I asked.

"The funny thing was that he never seemed to see my difficulty. When I
kept bringing him back to it he shied off with a new wild theory of
perception. He argued that the mind can live in a world of realities
without any sensuous stimulus to connect them with the world of our
ordinary life. Of course that wasn't my point. I supposed that this
world of Space was real enough to him, but I wanted to know how he got
there. He never answered me. He was the typical Cambridge man, you
know--dogmatic about uncertainties, but curiously diffident about the
obvious. He laboured to get me to understand the notion of his
mathematical forms, which I was quite willing to take on trust from
him. Some queer things he said, too. He took our feeling about Left
and Right as an example of our instinct for the quality of Space. But
when I objected that Left and Right varied with each object, and only
existed in connection with some definite material thing, he said that
that was exactly what he meant. It was an example of the mobility of
the Spacial forms. Do you see any sense in that?"

I shook my head. It seemed to me pure craziness.

"And then he tried to show me what he called the 'involution of Space,'
by taking two points on a piece of paper. The points were a foot away
when the paper was flat, they coincided when it was doubled up. He
said that there were no gaps between the figures, for the medium