Hieronymus Bosch and other early Renaissance artists depicted 'stone operations' in which stones were supposedly surgically removed from the head as a treatment for mental illness. These works have usually been interpreted either as portraying a contemporary practice of medical charlatans or as an allegory of human folly, rather than a real event. As trepanation for head injury and mental disease was actually carried out in Europe at this time, another interpretation of these works is that they are derived from a common medical practice of the day.