"This thing," he said, "acts automatically."

"You needn't tell me," I said. "I know exactly what it will do, by
instinct. Going uphill it will jamb the wheel so effectively that we
shall have to carry the machine bodily. The air at the top of the hill
will do it good, and it will suddenly come right again. Going downhill
it will start reflecting what a nuisance it has been. This will lead to
remorse, and finally to despair. It will say to itself: 'I'm not fit to
be a brake. I don't help these fellows; I only hinder them. I'm a
curse, that's what I am;' and, without a word of warning, it will 'chuck'
the whole business. That is what that brake will do. Leave it alone.
You are a good fellow," I continued, "but you have one fault."

"What?" he asked, indignantly.

"You have too much faith," I answered. "If you read an advertisement,
you go away and believe it. Every experiment that every fool has thought
of in connection with cycling you have tried. Your guardian angel
appears to be a capable and conscientious spirit, and hitherto she has
seen you through; take my advice and don't try her too far. She must
have had a busy time since you started cycling. Don't go on till you
make her mad."

He said: "If every man talked like that there would be no advancement
made in any department of life. If nobody ever tried a new thing the
world would come to a standstill. It is by--"

"I know all that can be said on that side of the argument," I
interrupted. "I agree in trying new experiments up to thirty-five;