John Fletcher,
Studies on Slavery, in Easy Lessons
“ And who shall say that the wicked, disgusting mode of life, the practices deteriorating the physical and mental powers imputed to the Cainites, do not constitute what some may call a philosophical cause of the physical development of the mark of sin? Does not our own observation teach us that a single lifetime, spent in the practice of some degrading sins, leaves upon the person the evidence, the mark, the proof of such practice? We are under no compulsion of evidence or belief to suppose that the mark set upon Cain was the product of a moment ”
