That's the point.

D'you mean to tell me--" "I mean that I don't care for anything else in the whole world," said Frank, stung with sudden enthusiasm.
"But ...

but you're not mad! You're a very sensible, fellow.

You don't mean to tell me you really believe all that--all that about pain and so on?
We doctors know perfectly what all that is.

It's a reaction of Nature ...