Insanity, craziness, or madness, is a spectrum of behaviors characterized by certain abnormal mental or behavioral patterns. Insanity may manifest in people as violations of societal norms, including becoming a danger to themselves and others, though not all such acts are considered insanity. In modern usage insanity is most commonly encountered as an informal unscientific term denoting mental instability, or in the narrow legal context of the insanity defense.
- Have I need of mad men, that ye have brought this fellow to play the mad man in my presence?
- Achish king of Gath, Bible, Samuel I, 21:15
- All schizophrenia patients are mad, and none are sane. Their behaviour is incomprehensible. It tells us nothing about what they do in the rest of their lives, gives no insight into the human condition and has no lesson for sane people except how sane they are. There's nothing profound about it. Schizophrenics aren't clever or wise or witty — they may make some very odd remarks but that's because they're mad, and there's nothing to be got out of what they say. When they laugh at things the rest of us don't think are funny, like the death of a parent, they're not being penetrating, and on other occasions they're not wryly amused at at the simplicity and stupidity of the psychiatrist, however well justified that might be in many cases. They're laughing because they're mad, too mad to be able to tell what's funny any more. The rewards for being sane may not be very many but knowing what's funny is one of them. And that's an end of the matter.
- Kingsley Amis, Stanley and the Women, p. 147.
- Love: A temporary insanity curable by marriage or by removal of the patient from the influences under which he incurred the disorder. This disease is prevalent only among civilized races living under artificial conditions; barbarous nations breathing pure air and eating simple food enjoy immunity from its ravages. It is sometimes fatal, but more frequently to the physician than to the patient.
- Insanity is relative. It depends on who has who locked in what cage.
- I'm seventeen and I'm crazy. My uncle says the two always go together. When people ask your age, he said, always say seventeen and insane.
- Insanity is repeating the same mistakes and expecting different results.
- From Narcotics Anonymous circa 1980; in print in an 1981 "approval version" of the Narcotics Anonymous "Basic Text" – see that page for details.
- This and variations on it have also been variously attributed to Benjamin Franklin, Albert Einstein, Rita Mae Brown, and an old Chinese proverb, but this is the earliest known appearance and probable origin.
- When life itself seems lunatic, who knows where madness lies? Perhaps to be too practical is madness. To surrender dreams — this may be madness. To seek treasure where there is only trash. Too much sanity may be madness — and maddest of all: to see life as it is, and not as it should be!
- Miguel de Cervantes, "Man of La Mancha".
- In women, courage is often mistaken for insanity.
- Doctor in Iron Jawed Angels.
- You are right, Mr. Bond.
That is just what I am, a maniac.
All the greatest men are maniacs.
They are possessed by a mania that drives them towards their goal.
The great scientists, the philosophers, the religious leaders — all maniacs.
- The days of visitation are come, the days of recompence are come; Israel shall know it: the prophet is a fool, the spiritual man is mad
- Hosea 9:7
- If we are all insane, then all insanity becomes a matter of degree. If your insanity leads you to carve up women like Jack the Ripper or the Cleveland Torso Murderer, we clap you away in the funny farm (except neither of those two amateur-night surgeons were ever caught, heh-heh-heh); if, on the other hand, your insanity leads you only to talk to yourself when you're under stress or to pick your nose on your morning bus, then you are left alone to go about your business...although it's doubtful that you will ever be invited to the best parties.
- Mental illness is in the eye of the beholder.
- "Prot" in "K-PAX" (1995).
- There is a thin line between genius and insanity. I have erased this line.
- Oscar Levant, as quoted in Celebrity Register : An Irreverent Compendium of American Quotable Notables (1959) by Cleveland Amory ; also paraphrased as "There is a fine line between genius and insanity. I have erased this line".
- I'm standing on the edge of some crazy cliff. What I have to do, I have to catch everybody if they start to go over the cliff— I mean if they're running and they don't look where they're going I have to come out from somewhere and catch them. That's all I'd do all day. I'd just be the catcher in the rye and all. I know it's crazy, but that's the only thing I'd really like to be. I know it's crazy.
Hoyt's New Cyclopedia Of Practical Quotations 
- Quotes reported in Hoyt's New Cyclopedia Of Practical Quotations (1922), p. 396-97.
- Like men condemned to thunderbolts,
Who, ere the blow, become mere dolts.
- Samuel Butler, Hudibras, Part III (1678), Canto II, line 565.
- Much madness is divinest sense
To a discerning eye;
Much sense the starkest madness.
'Tis the majority
In this, as all, prevails
Assent, and you are sane;
Demur,—you're straightway dangerous,
And handled with a chain.
- Emily Dickinson, Poems, XI. (Ed. 1891).
- For those whom God to ruin has designed
He fits for fate, and first destroys their mind.
- John Dryden, Fables, The Hind and the Panther (1687), Part III, line 2,387.
- There is a pleasure, sure,
In being mad, which none but madmen know!
- John Dryden, Spanish Friar, Act II, Stanza 1.
- The alleged power to charm down insanity, or ferocity in beasts, is a power behind the eye.
- Ralph Waldo Emerson, Essays, Conduct of Life. Of Behaviour.
- At dæmon, homini quum struit aliquid malum,
Pervertit illi primitus mentem suam.
- But the devil when he purports any evil against man, first perverts his mind.
- Euripides, fragment 25. Barnes Ed. Attributed to Athenagorus. Also ed. pub. at Padua, 1743–53, Volume X, p. 268. The Translator. P. Carmeli, gives the Italian as: Quondo vogliono gli Dei far perire alcuno, gli tiglie la mente.
- But when Fate destines one to ruin it begins by blinding the eyes of his understanding.
- James Fraser, Short History of the Hindostan Emperors of the Moghol Race (1742), p. 57. See also story of the Christian Broker. Arabian Nights. Lane's translation. Ed. 1859, Volume I, p. 307.
- Mad as a March hare.
- James Halliwell-Phillipps, Archaic Diet, Volume II. Art. "March Hare." Heywood—Proverbs, Part II, Chapter V. Skelton—Replycacion Agaynst Certayne Yong Scolers, etc, line 35.
- Doceo insanire omnes.
- I teach that all men are mad.
- Horace, Satires, II. 3. 81.
- Nimirum insanus paucis videatur, eo quod
Maxima pars hominum morbo jactatur eodem.
- He appears mad indeed but to a few, because the majority is infected with the same disease.
- Horace, Satires, II. �. 120.
- Quisnam igitur sanus? Qui non stultus.
- Who then is sane? He who is not a fool.
- Horace, Satires, II. 3. 158.
- O major tandem parcas, insane, minori.
- Oh! thou who art greatly mad, deign to spare me who am less mad.
- Horace, Satires, II. 3. 326.
- I demens! et sævas curre per Alpes,
Ut pueris placeas et declamatio fias.
- Go, madman! rush over the wildest Alps, that you may please children and be made the subject of declamation.
- Juvenal, Satires, X, 166.
- O, hark! what mean those yells and cries?
His chain some furious madman breaks;
He comes—I see his glaring eyes;
Now, now, my dungeon grate he shakes.
Help! Help! He's gone!—O fearful woe,
Such screams to hear, such sights to see!
My brain, my brain,—I know, I know
I am not mad but soon shall be.
- Matthew Gregory Lewis ("Monk Lewis"), The Maniac.
- Id commune malum; semel insanivimus omnes.
- It is a common calamity; at some one time we have all been mad.
- Baptista Mantuanus, Eclogue I.
- My dear Sir, take any road, you can't go amiss. The whole state is one vast insane asylum.
- James L. Petigru, on being asked the way to the Charleston, South Carolina Insane Asylum (1860).
- Hei mihi, insanire me ajunt, ultro cum ipsi insaniunt.
- They call me mad, while they are all mad themselves.
- Plautus, Menæchmi, V, 2, 90.
- Nullum magnum ingenium sine mixtura dementiæ fuit.
- There has never been any great genius without a spice of madness.
- Seneca, De Animi Tranquillitate, XV. 10.
- Quid est dementius quam bilem in homines collectam in res effundere.
- What is more insane than to vent on senseless things the anger that is felt towards men?
- Seneca, De Ira, II. 26.
- Madam, I swear I use no art at all.
That he is mad, 'tis true, 'tis true 'tis pity;
And pity 'tis 'tis true.
- Though this be madness, yet there is method in 't
- It shall be so:
Madness in great ones must not unwatch'd go.
- I am not mad; I would to heaven I were!
For then, 'tis like I should forget myself.
- We are not ourselves
When nature, being oppress'd, commands the mind
To suffer with the body.
- Were such things here as we do speak about?
Or have we eaten on the insane root
That takes the reason prisoner?
- You will never run mad, niece;
No, not till a hot January.
- Fetter strong madness in a silken thread.
- Quem Jupiter vult perdere, dementat primus.
- Whom Jupiter would destroy he first drives mad.
- Sophocles, Antigone, Johnson's ed. (1758), line 632. Sophocles quotes it as a saying. The passage in Antigone is explained by Tricinius as "The gods lead to error him whom they intend to make miserable." Quoted by Athenagoras in Legat, p. 106. Oxon Ed. Found in a fragment of Æschylus preserved by Plutarch—De Audiend. Poet, p. 63. Oxon ed. See also Constantinus Manasses. Fragments, Book VIII, line 40. Ed. by Boissonade. (1819). Duport's Gnomologia Homerica, p. 282. (1660). Oracula Sibylliana, Book VIII, line 14. Leutsch and Schneidewin—Corpus Paræmiographorum Græcorum, Volume I, p. 444. Sextus Empiricus is given as the first writer to present the whole of the adage as cited by Plutarch. ("Concerning such whom God is slow to punish.") Hesiod—Scutum Herculis. V. 89. Note by Robinson gives it to Plato. See also Stobæus—Germ, II. de Malitia.
- Insanus omnis furere credit ceteros.
- Every madman thinks all other men mad.
- Syrus, Maxims.
- Mad as a hatter.
- William Makepeace Thackeray, Pendennis, Chapter X.
Legal insanity 
- A human creature deprived of reason, and disordered in his senses, is still an animal, or instrument possessing strength and ability to commit violence; but he is no more so than a mere mechanical machine, which, when put in motion, performs its powerful operations on all that comes in its way, without consciousness of its own effects, or responsibility for them. In like manner, the man under the influence of real madness, has properly no will, but does what he is not conscious or; sensible he is doing, and therefore cannot be made answerable for any consequences.
- Lord Eskgrove, Kinloch's Case (1795), 55 How. St. Tr. 1000; reported in The Dictionary of Legal Quotations (1904), p. 105.
- Hamlet, being charged with " coinage of the brain" answers:
- "It is not madness
- That I have uttered; bring me to the test,
And I the matter will re-word; which madness
Would gambol from."
- Madness, then, varies and fluctuates: it cannot "re-word"—if the poet's observation be well founded; and though the Court would not at all rely upon it as an authority, yet it knows from the information of a most eminent physician that this test of madness, suggested by this passage, was found, by experiment in a recent case, to be strictly applicable, and discovered the lurking disease.
- Sir John Nicholl, Groom v. Thomas (1829), 2 Hagg. Ecc. Rep. 452, 453; reported in The Dictionary of Legal Quotations (1904), p. 104-05. The reference goes on to say:
The Court was understood to allude to the case referred to in a note to p. 242, of the 10th number of the new series of the Quarterly Journal of Sciences and the Arts, London, 1829. "If the tests of insanity are matters of law, the practice of allowing experts to testify what they are should be discontinued; if they are matters of fact, the Judge should no longer testify without being sworn as a witness and showing himself qualified to testify as an expert."—Doe, J., State v. Pike, 49 New Hamp. Eep. 399 ; 6 Amer. Eep. 584.
- Is not this insanity plea becoming rather common? Is it not so common that the reader confidently expects to see it offered in every criminal case that comes before the courts? [...] Really, what we want now, is not laws against crime, but a law against insanity.
- Because the insanity defense is a key part of our criminal-justice system, which is founded on the belief that people normally choose whether or not to obey the law. Certain people, we have said historically, cannot make that choice, however, either because they are too young or because of severe mental retardation or mental illness. The insanity defense exists in practically every civilized country. It is not some kind of aberration, as some seem to be suggesting in the wake of the Hinckley verdict.
- Elyce Zenoff Ferster, answering an interview question in U.S. News & World Report, Volume 93 (1982), p. 15; reported in Alan F. Pater, Jason R. Pater, What They Said in 1982: The Yearbook of World Opinion (1983).