The best doctors in the world are Doctor Diet, Doctor Quiet, and Doctor Merryman.
Jonathan Swift (1667-1745) English writer and churchman
Polite Conversation, Dialog 2 (1738)
Borrowed / popularized from William Bullein, Government of Health, folio 50 (1558): "The first was called doctor diet, the seconde doctor quiet, the thirde doctor merry-man." (1558)