Transition from humoral physiology to psychological state
Early modern texts define melancholy as a cold, dry humor or physiological condition, whereas later psychological texts treat it as a subjective state of morbidity, sadness, or religious experience.
that is, the hot and fiery humour in a body so hot of temper, which Phlegm or Melancholy could not effect.Pseudodoxia Epidemica →
Often they have led a discordant inner life, and had melancholy during a part of their career.The Varieties of Religious Experience →