Stone of madness

The stone of madness, also called stone of folly, was a hypothetical stone in a patient's head, thought to be the cause of madness, idiocy or dementia. From the 15th century onwards, removing the stone by trepanation was proposed as a remedy.^[1][2] This procedure is demonstrated in the painting The Extraction of the Stone of Madness by Hieronymus Bosch.^[3]

Hieronymus Bosch, The Extraction of the Stone of Madness

Gallery

• 
  Quentin Massys, An Allegory of Folly (early 16th century). The fool has a "stone of folly" in his forehead.
• 
  Pieter Huys, A surgeon extracting the stone of folly
• 
  Jan Sanders van Hemessen, 1550s
• 
  After Hieronymus Bosch, 16th century
• 
  Pieter Jansz. Quast,
  Die Steinoperation, ca 1630