J C Prichard's concept of moral insanity--a medical theory of the corruption of human nature.

In the eighteenth century, insanity was widely explained within the Lockean philosophical framework of enlightened rationality: delusions or illusions, basically erroneous thinking, led human reason into the wrong. By the beginning of the nineteenth century, after the French Revolution and in the midst of the transformations which the industrial revolution brought about, new theories of insanity emerged. The realm of unsoundness changed its character and became as unfathomable as the epoch appeared to many who were witnessing it. Increasingly, cases of insanity became known where the patients did not seem to dwell in some delusive state. They displayed deep sullenness, unmitigated fury, utter shamelessness, seemingly without either purpose or motivation. One of the constructs newly used to explain the evidence was the concept of moral insanity. It referred to a derangement of those mental faculties which presided over man's emotive framework as well as his moral faculty. It was formulated by the Bristol doctor James Cowles Prichard (1786-1848), who put it forward first in 1833, in an article in The cyclopaedia ofpractical medicine.' In the Treatise on insanity, published in 1835, he gave his account of medical knowledge on madness,2 inscribing moral insanity into medical nosology and embedding the doctrine in his medical philosophy. In the course of his elaborations of the concept, Prichard presented a number of case studies which he had solicited from other doctors in order to prove his theory. One of these was the case of "a gentleman" provided by his Bristol colleague, John Addington Symonds, who reported that: