“There are some things which it is madness not to try to know but which it is almost as much madness to try to know.”

Source: The Stand

Wood, Christopher. "Terrible Hard", Says Alice. London: Constable. 1970. (chapter 11)

Source: The Paying Guests

De Abaitua interview (1998)
Context: The magician to some degree is trying to drive him or herself mad in a controlled setting, within controlled laws. You ask the protective spirits to look after you, or whatever. This provides a framework over an essentially amorphous experience. You are setting up your terms, your ritual, your channels – but you deliberately stepping over the edge into the madness. You are not falling over the edge, or tripping over the edge.
When I was a kid, I used to go to the seaside and play in the waves. The thing you learn about waves, is that when you see a big one coming, you run towards it. You try and get out of its way and you’ll end up twenty yards up the beach covered in scratches. Dive into it, and then you can get behind it. You get on top it, you won’t be hurt. It is counter-intuitive, the impulse is to run away, but the right thing to do is to plunge into it deliberately, and be in control when you do it. Magic is a response to the madness of the twentieth century.

Source: Cronenberg on Cronenberg (1997), Ch. 1, P. 7

The New-York Magazine (November 1791) p. 662.
On being warned by the Duke of Newcastle, in 1758, against promoting James Wolfe. Often quoted as "Mad, is he? Then I hope he will bite some of my other generals."

Source: Persuasion