A Treatise on the Crime of Onan: Illustrated with a Variety of Cases, Together with the Method of Cure

In Short

This medical treatise functions as a stern warning against the perceived physiological dangers of masturbation, which the author categorizes as a "crime" against the body. By compiling case studies and drawing on contemporary anatomical theories, it argues that the loss of "seminal humor" drains the nervous system, leading to blindness, epilepsy, madness, and eventual death. The work is historically significant for its rigid attempt to bridge the gap between moral failing and physical pathology, establishing a framework that influenced European social attitudes toward sexual hygiene for over a century.

The Story

The narrative arc begins with a stark, diagnostic premise: the body is a closed system of vital fluids and animal spirits. The author introduces the central conflict by asserting that the unnatural evacuation of seminal fluid—specifically through masturbation—acts as a violent theft of the body’s essential energy. This is not presented merely as a moral lapse, but as a mechanical disruption of the nervous system. The opening chapters establish the "symptoms" of this depletion, which include pallor, memory loss, stomach weakness, and the dimming of the senses.

As the text progresses, it deepens the medical dread by detailing the "variety of cases" observed in clinical practice. These accounts describe patients who, after abandoning themselves to the habit, descend into hypochondria, hysterical suffocation, and total bodily rigescence—a state of catatonic stiffness. The author invokes the authority of classical physicians and contemporaries, building a cumulative argument that the "crime" is a biological catastrophe. He contrasts these self-polluters with those who engage in "natural" intercourse, arguing that the psychological joy associated with legitimate love acts as a restorative force, whereas solitary acts are defined by "remorse" and "horror," which only accelerate the decay.

The argument then shifts toward the "Method of Cure." Having established the nature of the affliction, the author outlines a rigid therapeutic regimen. This involves the complete cessation of the practice, a strict diet focused on strengthening the fibers (avoiding heavy or overly liquid foods), and the use of tonics like the Peruvian bark. The narrative reaches its resolution not in a dramatic climax, but in a series of procedural guidelines for the physician. The author emphasizes that while some patients may be beyond help, the majority can recover if they adhere to a life of physical and moral discipline. The conclusion is an appeal to the reader to view sexual restraint as a fundamental requirement for the preservation of the intellect and the vigor of the physical form.

How It Unfolds

The medical diagnosis The text opens by framing the loss of seminal fluid as a depletion of "animal spirits," asserting that the body’s vitality is inextricably linked to the retention of these fluids. It presents this not as a theological debate, but as a cold, mechanical reality where the nervous system is overwhelmed by the act.

The catalog of symptoms The middle section documents the "dreadful accidents" that befall those who transgress these natural laws. The author meticulously lists physical signs—from pimples and blotches to the total decay of sight and hearing—to illustrate the systemic collapse of the patient.

The comparative analysis The argument expands to categorize other "deviations," including what the author terms "clitoridian" contamination. He distinguishes between the "natural" act, which is mitigated by emotional connection, and the "solitary" or "monstrous" act, which he claims is inherently more damaging due to the lack of joy.

The prescriptive remedy The final chapters focus entirely on the recovery process, detailing specific dietary restrictions, the necessity of cold baths, and the importance of avoiding sedentary habits. It concludes with a pragmatic set of instructions for the physician to guide the patient back to health through rigorous behavioral modification.

The People

The book features a cast of "patients" rather than characters, each serving as a cautionary exhibit. These figures are usually men in the prime of life who have "abandoned" themselves to their habits. They are defined by their weakness—a "paleness" of the face and a "confusion" of the intellect. They possess a desire for health but find themselves trapped by a physiological reflex that has become a master over their will.

Contrasted against these patients are the "observers"—the physicians like Boerhaave, Hoffman, and the author himself. These figures act as the rational agents of the text. They are cool, detached, and armed with the "exact theory" of medicine. They represent the voice of authority, identifying the symptoms and prescribing the cure. They do not view the patients with malice, but with a clinical melancholy, treating the "crime" as a disease to be managed rather than a sin to be castigated. Ultimately, the patient is a blank slate who, through the intervention of the physician and the adoption of a "regular" lifestyle, is either restored to a state of "virility" or allowed to "go out like a taper" if the damage has been too great.

In Its Own Voice

The author highlights the immediate physiological toll of the act on the nervous system:

"Nothing (says a celebrated Physician of Louvain) so much weakens the vital faculties, and abridges life."

The author emphasizes the psychological weight of the act, noting that unlike natural relations, this specific behavior is tainted by internal distress:

"Wretched are those joys which are obnoxious to remorse!"

He reflects on the total physical destruction of a patient who had long abandoned himself to the practice:

"Uncapable of lying on the bed in any other posture but the supine one, and without power to move hand or foot, immoveable, in short, and reduced to receive no aliments but as they were put into his mouth; he languished a few weeks in this deplorable condition, and died, or rather went out like a taper, almost without any indication of pain."

What It's Really About

The central theme is the Enlightenment attempt to colonize human desire with the language of science. By rebranding a moral transgression as a "morbid" condition, the author argues that the body is a machine that must be regulated to ensure the productivity and survival of the individual. The work explores the question of whether the "soul" and the "body" can be separated; the author concludes they cannot, as every moral action leaves a chemical footprint on the nervous system. It is a treatise on the anxiety of the period—the fear that self-indulgence would lead to a generation of weak, "emaciated" individuals, thereby threatening the health of the social and physical body politic.

Why Read It Today

This text is an essential artifact for anyone interested in the history of medicine, sexual ethics, or the social construction of "normality." Reading it today provides a chilling look at how easily moral judgment can be cloaked in the authoritative language of "symptoms," "tonics," and "physiological laws." The prose is precise and clinical, though it carries a heavy, archaic tone that may feel alienating to a modern reader. It is not an easy read; the author’s insistence on cataloging every possible physical ailment—from "fleshy excrescences" to "strangury"—can be repetitive and, at times, deeply distressing.

However, the book stays with you because it illuminates a fundamental shift in how humanity has viewed the self. You see a world where the "animal spirits" are the currency of a life well-lived, and where the physician acts as the warden of the body. While the science is archaic and the attitudes are narrow, the work is a masterpiece of its own specific, rigid logic. It serves as a reminder of how medical consensus can change over centuries, turning what was once considered a terminal, criminal pathology back into a normal aspect of human life. It is a demanding, dark, and fascinating window into the past.