Source, in full
Reported by many sites to have been said by Chaplin upon signing the papers to create the United Artists studio (1919), this is believed to actually be derived from a remark about the same event attributed to Richard Rowland, the head of Metro Pictures: "The lunatics have taken charge of the asylum"; variant derivations or reports of this statement also include "The lunatics have taken over the asylum", and the attribution to Rowland is reported to have occurred at least as early as 1926, in the work A Million and One Nights by Terry Ramsaye, and as recently as in Variety (16 October 2005)
Notes from Wikiquote
David Robinson In Charlie Chaplin: Comic Genius (1996), p. 57, also asserts that a disgruntled film distributor said "The lunatics are taking over the asylum."