Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class IV. Words Relating to the Intellectual Faculties
Division (I) Formation of Ideas
Section V. Results of Reasoning

504. Madman.

   NOUN:MADMAN, lunatic, maniac, bedlamite, candidate for Bedlam, raver, phrenetic, madcap; energumen [eccl. antiq.]; automaniac, monomaniac, dipsomaniac, kleptomaniac, paranoiac; hypochondriac (low spirits) [See Dejection]; crank [colloq.], Tom o’ Bedlam; nut [slang].
  DREAMER [See Imagination]; rhapsodist, seer, highflyer or highflier [obs.], enthusiast, fanatic, fanatico [It.], exalté [F.], Don Quixote, Ophelia, Madge Wildfire.
  IDIOT [See Fool].
  1. The lunatic, the lover, and the poet Are of imagination all compact.—Midsummer’s Night’s Dream
  2. There is a pleasure, sure, In being mad, which none but madmen know.—Dryden
  3. O, what a noble mind is here o’erthrown!—Hamlet
  4. Who knows of madness whether it is divine or whether it be of the pit.—Dunsany