Below is an abridged extract of an actual lecture delivered (around 1797) by Benjamin Rush,
"Father of American Psychiatry" and whose picture still adorns the seal of the
American Psychiatric Association

Gentlemen of the American Philosophical Society, my talk today is entitled
“Observations intended to prove that the colour of our fellow creatures known by the epithet of Negroes is derived entirely from a modification of the disease known as Leprosy”.

Now Gentlemen, with your permission, I shall briefly enumerate the wide range of circumstances that make this probable.
First, the leprosy IS accompanied often by a black colour of the skin. According to the excellent physician, Dr Theiry, in one of the species of the disorder, there is no pustules, or scales, no emaciation of the body, but the breathing is difficult and the countenance some fierceness in it. The sufferer perpetually exhales a peculiar and disagreeable smell, which I can compare only to that of a mortified limb.”
This smell as we know, gentlemen, continues in the native African today.
Secondly: the original connection of the black colour of the Negroes with the leprosy is further suggested by the facts of Mr Bougainville’s voyage. He visited a Pacific Island and the inhabitants, composed largely of negroes, had thick lips, woolly hair, and were sometimes a yellowish colour. They were short, ugly, ill proportioned, and most of them infected with the leprosy.
Thirdly: The leprosy induces a morbid insensibility in the nerves. Hence the common saying, “he has no more feeling than a leper’. This insensibility, as we know, belongs also to the negro. Dr Mosely has written, “they are void of sensibility to a surprising degree. They bear surgical operations much better than white people, and what would be a cause of insupportable pain to a white man, a negro would almost disregard. I myself have amputated the legs of many negroes, who have held the upper part of the limb themselves.”
Fourth: Lepers are remarkable for having strong venereal desires. This is UNIVERSAL among the negroes, hence their uncommon fruitfulness when they are not depressed by slavery; but even slavery in its worst state does not subdue the venereal appetite, for after whole days, spent in hard labour in the hot sun of the west Indies, the black men often walk five or six miles to comply with a venereal assignation.’
Fifth: The big lip, and flat nose so universal among the negroes are symptoms of the leprosy. I myself have, more than once, seen them in the Pennsylvania hospital.


Now should it be objected that the leprosy is an infectious disorder when no infectious quality exists in the skin of the negro, I reply by remarking that in the first place, the leprosy has in a great degree ceased to be infectious, (more especially from contact), and secondly that there ARE instances in which something like an infectious quality has appeared in the skin of a negro. A white woman…in North Carolina, gentlemen, not only acquired a dark colour, but several of the features of a negro, by marrying and living with a black husband. A similar instance of a change in the colour and features, of a woman, in Buck’s county, Pennsylvania has been observed, and from a similar cause. In both these cases, the women bore children to their black husbands.

And it is no objection to my theory that the negroes are as healthy and long-lived as white people. Dr Theiry remarks that the leprosy did not impair the longevity of those people whom he studied.

The facts and principles that I have delivered lead to the following reflections…
1. That all claims of superiority of the whites over the blacks, on account of their colour, are founded alike in ignorance and inhumanity. If the colour of the negro be the effect of a disease, instead of inviting us to tyrannise over them, it should entitle them to a double portion of our humanity. For disease has always been the signal for universal compassion.
2. The principles and facts that I have delivered to you gentlemen should teach white people the necessity of keeping up that prejudice against such connections with the negro of a personal nature, as it would tend to infect future generations with some portion of their …disorder.
3. If the colour of the negroes is a disease, then let science discover a remedy for it. Nature herself has recently unfurled a banner upon this subject. For she has begun spontaneous cures of this disease in several black people in this country. In a certain Henry Moss, who lately travelled through this city, and who was exhibited as a show for money, the cure was nearly complete. The change from black to a natural white flesh colour began about five years ago at the end of his fingers, and has extended gradually over the greatest part of his body. The wool on his head has been changed into hair.


Now, finally gentlemen… to direct our experiments on this subject, I shall offer the following facts.

1. In Henry Moss, the colour was first discharged from the skin in those places on which there was most pressure from clothing, and most attrition from labour, as on the trunk of his body and on his fingers. The destruction of the black colour was probably occasioned by the absorption of the colouring matter. It is from the latter cause that the palms of the hands of the negro women, who spend their lives at a washing tub, are generally as fair as the hands in labouring white people.
2. Depletion, whether by the most excellent practice of bleeding, of purging, or of abstinence has often been observed to lessen the black colour in negroes.
3. A similar lessening in the black colour, although of a more temporary nature, has often been observed from using the influence of fear.
4. Dr Beddoes tells us that he has discharged the colour in the black wool of a negro by infusing it in oxygenating muriatic acid, and lessened the colour in the skin of the hand of a negro man by the same method.
5. A citizen of Philadelphia upon whose veracity I have perfect reliance assured me that he had once seen the skin of one side of the cheek and the chin and the hand of a negro boy, changed to a white colour when the juice of unripe peaches (of which he ate a large quantity every year) did frequently fall and rest upon those parts of his body.

To encourage attempts to cure this disease of the skin in negroes, let us recollect that by succeeding in these attempts we shall produce a large portion of happiness in the world. We shall in the first place destroy one of the arguments for enslaving the negroes, for their colour has been supposed by the ignorant to mark them as objects of divine judgements, and by the learned to qualify them for nothing but labour in hot, and unwholesome climates.
Secondly, we shall add greatly to their happiness, for however well they appear to be satisfied with their colour, there are many proofs for their preferring that of the white people.
Thirdly, we shall render easy and universal the belief that the whole human race is descended from one pair, and thereby not only add weight to the Christian revelation, but also remove a material obstacle to the exercise of that universal benevolence which is inculcated by it.
(June 17th 1797.)