The Crime of Onan and the Laws of Nature. Religious and medical discourses on masturbation in the late seventeenth and early eighteenth centuries

This article takes a closer look at the arguments and intellectual context of theological and medical discourse on masturbation in the early stages of the anti‐masturbation campaign, from about 1680 to 1730. It identifies a first stage, during which moralist and religious writing dominated the campaign. The authors used medical arguments on the fatal health hazards of masturbation in support of their message. But the crucial shift in religious discourse on masturbation compared to previous times was the emphatic association of masturbation with the sin of Onan. This shift is linked, in particular, to the rise of traducianist accounts of human conception among Protestant theologians of the sixteenth and seventeenth centuries. While traditional Aristotelian and Thomistic philosophy claimed that the rational human soul was created and infused by God only weeks after conception, traducianists saw the parental semen itself as the decisive vehicle for the transmission of the immortal human soul. Within this framework, the ontological and theological status of semen changed markedly. Traducianism remained far from being universally accepted, but it created a growing readiness to accept that the immortal soul was at least potentialiter in the semen. Masturbation came much closer to murder, or was even explicitly condemned as such. The deadly punishment which God had inflicted on Onan for having spilled his semen was fully justified. During a second stage, from about 1710, medical arguments increasingly took the forefront. A group of London venereal specialists elaborated on occasional earlier claims that masturbation damaged the genital vessels and fibres, bringing forth impotence, seminal efflux and gleets with devastating long‐term effects on the whole body. John Marten, the anonymous author of “Onania” and various members of the venereal trade published extensively on the topic and popularised the issue of masturbation and its health effects on an unprecedented scale. At the same time, they further strengthened the link between masturbation and the sin of Onan. Like Onan (and his brother Er), every “onanian” would bring death upon himself. In parallel development, some academic physicians began to question the validity of traditional fears of “seminal retention” and with it the traditional idea that according to the laws of nature seminal emissions sometimes might also have a beneficial effect on physical health. Rather than putrefying in the body, the semen was said to recirculate into the body after its preparation in the seminal vessels and served an indispensable re‐invigorating function. It was responsible for the typical masculine traits of the male body. Divine law and natural law now fully coincided.