“…For example, as Eric Herschthal explains in his study of Rush's contribution to abolition advocacy, Rush thought that black skin was caused by the disease of leprosy. 80 But Rush also thought that the effects of the leprosy would be reversed, causing blacks to turn white, under conditions of liberation, exercise, and Christian instruction. Rush's theory of race was not typical of his time; contemporaries explained racial change and differentiation by "climate, geography, and social behavior" 81 rather than disease.…”