Witch hunts and trials are ingrained in our culture as a shocking example of mob psychology. The cruelty and panic unleashed upon the misfits of a community are documented in records such as Malleus Maleficarum and Daemonologie by King James I.

One such chronicler of the early modern witch trials was the Dutch physician Johann Weyer, famous for his text De praestigiis daemonum. In his book, Weyer put that although evil demonic spirits did exist, those held under their power had some kind of behavioural deficit (Weyer used the term ‘melancholy’). Thus, he attributed the cause of the witches' behaviour not to Satanic influence, but to mental illness. He may have been the first physician to do so and to employ the term ‘mentally ill’. Weyer theorised that many admissions of wild orgiastic rituals were imagined by those psychologically predisposed to do so, describing such episodes as hallucinari (meaning ‘to let the mind run wild’ in Latin), symptoms of mental impairment.

Weyer recommended that when a person was accused of witchcraft, a physician should be consulted. This shift from the legal to the medical realm demonstrates Weyer's belief that the so-called witches did not have free will or capacity in their behaviour and could not be tried, which was an early case of diminished capacity defence. He asserted that the witches' illusions were by their nature unreal and thus the ‘witch’ could not be tried for them.

In his recommendations for the physician's consultation, Johann states that the physician should take a history during the examination and gives several case histories of his own. In some of these cases Weyer appears to advocate psychological management alone and assigns the cause of some of these mental illnesses to hallucinogens or an unstable temperament. Thus, Weyer produced and demonstrated a basic framework for physicians to examine the behaviour of an unwell patient rather than an organ system and attempted to establish pathological cause beyond superstition. However, the Catholic Church did not take well to Weyer's ideas and had De praestigiis daemonum banned.