Essays on Partial Derangement of the Mind in Supposed Connection with Religion, written amidst the illness of its author almost two centuries ago, was the little-known work of a distinguished physician. Seeking to rebut the argument that religion is causative of ‘derangement of the mind’ it takes a surprisingly biological view of such conditions while, at the same time, affirming the importance of faith, hope and love in human well-being. Despite its limitations, it makes observations that remain relevant to debates about religion and psychiatry today.