“When one person suffers from a delusion it is called insanity. When many people suffer from a delusion it is called Religion.”

“You suffer from the oldest delusion in politics. You think you can change the world by talking to a leader. Leaders are the effects, not the causes of changes.”

“[T]he Capgras delusion [is] a bizarre affliction that occasionally strikes human beings who have suffered brain damage. The defining mark of the Capgras delusion is the sufferer's conviction that a close acquaintance (usually a loved one) has been replaced by an impostor who looks like (and sounds like, and acts like) the genuine companion, who has mysteriously disappeared! … What is particularly surprising about these cases is that they don't depend on subtle disguises and fleeting glimpses. On the contrary, the delusion persists even when the target individual is closely scrutinized by the [Capgras sufferer], and is even pleading for recognition. Capgras sufferers have been known to murder their spouses, so sure are they that these look-alike interlopers are trying to step into their shoes — into whole lives — that are not rightfully theirs! There can be no doubt that in such a sad case, the [sufferer] in question has deemed true some very specific proposition of nonidentity: This man is not my husband; this man is a qualitatively similar to my husband as ever can be, and yet he is not my husband. Of particular interest to us is the fact that people suffering from such a delusion can be quite unable to say why they are so sure.”

“This is no world. It is God Himself. In delusion we call it world.”

“They suffered from the terrible delusion that something could be done. They seemed prepared to make the world the way they wanted it or die in the attempt, and the trouble with dying in the attempt was that you died in the attempt.”

“All are lunatics, but he who can analyze his delusion is called a philosopher.”

“They thought I suffered from lack of exterior, when I suffered from excess of interior”

“There are many kinds of delusion.”

“When a good man is hurt, all who would be called good must suffer with him.”

“When two people are under the influence of the most violent, most insane, most delusive, and most transient of passions, they are required to swear that they will remain in that excited, abnormal, and exhausting condition continuously until death do them part.”