Hans de Waardt is the leading scholar of witchcraft and its prosecution in Holland. De Waardt has also published a major study of the history of psychiatry as a discipline in the Netherlands and is currently pursuing research on the networks, correspondence and writings of key spiritualists. These include the famous Johann Wier (Weyer), author of the anti-witch prosecution treatise De praestigiis daemonum (The trickery of demons) of 1563 which argued that women accused of, or who voluntarily confessed to witchcraft, were suffering from a mental disturbance arising from a medical diagnosis of melancholia and should therefore be treated by a physician, not a legal court. De Waardt has recently uncovered spiritualistic connections for Wier, both in his personal network and in his writings. De Waardt’s most recent publication on the itinerant spiritualistic humanist Justus Velsius reveals that even the most idiosyncratic individual could have a widespread hearing and impact, even if much of this was at the time deemed a negative one. De Waardt will contribute to this program through his continuing archival work in uncovering spiritualistic networks and correspondence, and in discerning spiritualistic attitudes in published works.