A lunatic is just a minority of one.

The lunatic is all idée fixe, and whatever he comes across confirms his lunacy. You can tell him by the liberties he takes with common sense, by his flashes of inspiration, and by the fact that sooner or later he brings up the Templars.

Perhaps a lunatic was simply a minority of one. At one time it had been a sign of madness to believe that the Earth goes round the Sun; today, to believe the past is inalterable. He might be alone in holding that belief, and if alone, then a lunatic. But the thought of being a lunatic did not greatly trouble him; the horror was that he might also be wrong.

All primitive people thought that a lunatic was possessed by a spirit. When his incoherent words more or less accord with the moral prejudices of the time, the spirit is a good one, and the man i s a saint. In the opposite case, the spirit is evil and the man must be suppressed. It is just according to the time and place and the doctors, whether a prophetess would be worshipped as a priestess or ducked as a witch. Innumerable violent lunatics have escaped the cells, thanks to the War, and their very violence has made heroes of them. And in every Parliament there are at least five or six undisputed idiots who got elected for their madness through the admiration of their constituents.

There are four kinds of people in this world: cretins, fools, morons, and lunatics…Cretins don’t even talk; they sort of slobber and stumble…Fools are in great demand, especially on social occasions. They embarrass everyone but provide material for conversation…Fools don’t claim that cats bark, but they talk about cats when everyone else is talking about dogs. They offend all the rules of conversation, and when they really offend, they’re magnificent…Morons never do the wrong thing. They get their reasoning wrong. Like the fellow who says that all dogs are pets and all dogs bark, and cats are pets, too, therefore cats bark…Morons will occasionally say something that’s right, but they say it for the wrong reason…A lunatic is easily recognized. He is a moron who doesn’t know the ropes. The moron proves his thesis; he has logic, however twisted it may be. The lunatic on the other hand, doesn’t concern himself at all with logic; he works by short circuits. For him, everything proves everything else. The lunatic is all idée fixe, and whatever he comes across confirms his lunacy. You can tell him by the liberties he takes with common sense, by his flashes of inspiration, and by the fact that sooner or later he brings up the Templars…There are lunatics who don’t bring up the Templars, but those who do are the most insidious. At first they seem normal, then all of a sudden…

A cripple can still be a person, but in what sense is a lunatic human? Humanity’s in the mind, in the tangle of thoughts spun by the brain, and once that’s gone what remains is human only in outward shape.

Lunatics are writers whose works write them.

The ordinary lunatic is generally a harmless, isolated case; since everyone sees that something is wrong with him, he is quickly taken care of. But the unconscious infections of groups of so-called normal people are more subtle and far more dangerous.

—What was I thinking earlier about lunatics making their own version of truth? Why specify lunatics?

What causes the lunatic to demand that ideas not be subject to scrutiny—and in particular that they not be contradicted? No one knows. It may be part of a deliberate campaign to maintain power, an implicit admission of some semiconscious fear that the ideas might not be good, or just a common aspect of types of behavior that we associate with historical monsters. At least, the correlation is there.

“Anybody ever tell you you’re a lunatic?”
“Not in this context.”

Lunatics are similar to designated hitters. Often an entire family is crazy, but since an entire family can't go into the hospital, one person is designated as crazy and goes inside.

The difference between a humanist and a lunatic is in fact one of degree

Perhaps a lunatic was simply a minority of one.