The Fruits of Philosophy (1832), by Charles Knowlton

By: Claudia Nunez-Eddy
By: Caroline Meek

The Fruits of Philosophy (1832), by Charles Knowlton

In 1832, Charles Knowlton published The Fruits of Philosophy, a pamphlet advocating for controlling reproduction and detailing methods for preventing pregnancy. Originally published anonymously in Massachusetts, The Fruits of Philosophy was an illegal book because United States law prohibited the publishing of immoral and obscene material, which included information about contraception. In The Fruits of Philosophy, Knowlton detailed recipes for contraceptives and advocated for controlling reproduction. In 1877 in Europe, social activists Charles Bradlaugh and Annie Besant republished the pamphlet in London, England. At that time, many governments, including the United Kingdom, still considered the book illegal material due to its discussion of contraception. The Fruits of Philosophy was one of the first publications detailing contraceptive methods for controlling reproduction and activists used it in some of the first attempts at repealing obscenity laws in the United States and Great Britain. Through their efforts, Knowlton and those who later republished the pamphlet increased knowledge of reproduction and awareness of methods of contraception. By challenging anti-obscenity laws, the author and activists also helped with the eventual weakening and dissolution of such law.

Knowlton, a physician practicing in the United States, originally wrote The Fruits of Philosophy, also titled The Private Companion of Young Married People and A Treatise on the Population Question. Knowlton studied medicine at Dartmouth College in Hanover, New Hampshire in the 1820s. Following completion of his medical degree Knowlton moved to Ashfield, Massachusetts, where he practiced medicine and wrote the pamphlet. According to his autobiography, Knowlton wrote the short pamphlet-style guide to inform his patients about contraception and sex education. In 1932, Knowlton anonymously printed several copies of The Fruits of Philosophy and circulated them among his patients. That same year, Abner Kneeland, a theologian and social radical, republished The Fruits of Philosophy in Boston, Massachusetts with Knowlton’s name as the author on the cover, largely increasing circulation of the pamphlet. The government then charged Knowlton under the United States obscenity laws, which classified discussion of contraception as obscene. Knowlton was fined and imprisoned for three months in Cambridge, Massachusetts. Following his release, The Fruits of Philosophy was published again and Mason Grosvenor, a minister in Ashfield, found the pamphlet and took legal action to prevent the circulation of the material. Knowlton was tried again on obscenity charges, but the charges were later dropped. The trials increased the book’s publicity and more than one million copies were sold in America.

Following Knowlton’s death in 1850, circulation of The Fruits of Philosophy continued worldwide. In the 1850s, freethought activist James Watson published The Fruits of Philosophy in London, England. For many years, the pamphlet was published and sold throughout London unchallenged. In the 1870s, following the arrest of several publishers associated with publishing obscene materials, social activists Charles Bradlaugh and Annie Besant republished The Fruits of Philosophy, to test the validity of the pamphlet under England’s obscenity laws. Knowlton’s original work, The Fruits of Philosophy, has been republished many times throughout the world, however, the most commonly available edition is that published by Bradlaugh and Besant. In their “Publishers’ Preface,” Bradlaugh and Besant state that there are very few changes made to Knowlton’s original pamphlet and that all changes are clearly marked as deviations from the original. In the “Publisher’s Preface,” Bradlaugh and Besant also detail the history of the publication and the need for controlling reproduction in the wake of fears surrounding overpopulation and poverty.

Knowlton’s pamphlet, The Fruits of Philosophy, begins with a section titled “Philosophical Proem,” in which Knowlton discusses the basis and links between consciousness, sensations, passions, and human nature. He argues that humans have the power to prevent any evils that may arise from gratifying sexual desires, such as unwanted pregnancy and sexually transmitted diseases. He argues that it is unreasonable to solely advocate for abstinence to prevent pregnancy because humans are not likely to easily limit sexual gratification. Knowlton states that it is the duty of physicians to inform their patients of these prevention methods. Following that brief introduction, the pamphlet is organized into four chapters. In chapter one, Knowlton argues that controlling reproduction, the idea of conceiving children intentionally instead of accidentally, can be done without challenging any reproductive instincts. He defines reproductive instincts as the urge people have to have sex and reproduce. In chapter two, Knowlton asserts that every person has the right to information on reproduction and pregnancy prevention. He argues that the average person knows too little about the physiology of conception and reproduction. To educate his patients, Knowlton includes detailed descriptions of the reproductive organs and the physiological method of conception. In chapter three, he discusses several methods of contraception including recipes for chemical vaginal washes. Finally, in chapter four, Knowlton discusses why people have sex and argues that reproductive health includes sexual education, which was not common at the time.

In chapter one, Knowlton first discusses the political aspects of reproduction. He starts by referencing Thomas Malthus’ theory on overpopulation and poverty. Malthus, an economist, observed that population growth was exponential, and that as populations increased the lower class suffered in poverty, famine, and disease. Malthus argued that the only way a society could escape this increasing poverty was to restrict population growth. Knowlton explains the Malthusian idea, and states that war, disease, and famine keep populations in check and prevent overpopulation. He questions whether there can be other means to prevent overpopulation. Malthus argued in his work that the only way to combat population growth was through late marriage and celibacy. However, Knowlton explains that the belief that men and women will remain celibate is foolish. Knowlton argues that promoting celibacy and late marriage would actually increase prostitution, and be destructive to physical and mental health.

Knowlton then addresses the social aspects of reproduction, categorizing individuals as either married or not. He asserts that married couples often have many more children than they desire. Knowlton specifically addresses the health and wellbeing of the woman, stating that often a woman’s health, comfort, happiness, and life are endangered by multiple pregnancies. He also argues that married couples who should not become parents reproduce, specifically citing those with hereditary diseases. Knowlton then addresses the social aspect of population control among unmarried youth. He asserts that young men often oppose early marriage, desiring first to make enough money to support a family. However, he argues that young men are unlikely to resist the temptation of sexual gratification and will instead resort to prostitution. To prevent sexual temptation outside of marriage, Knowlton states individuals should marry young and be provided with the knowledge and means to prevent having children early in marriage. Knowlton uses the first chapter to comment on the importance of having the knowledge and means to prevent pregnancy to live the happiest life.

In chapter two, Knowlton states his belief that all individuals have a human right to receive the knowledge of the facts and discoveries made by science, including those of reproduction. He argues that knowledge about reproduction is important because reproduction is very connected to the happiness of humankind, yet he acknowledges that public discussion and investigation of topics like sex are considered improper. He goes on to discuss how the average person’s understanding of conception is lacking, and he states that that lack motivated him to write The Fruits of Philosophy.

As chapter two continues, Knowlton provides detailed descriptions of the external and internal reproductive organs in both males and females. He uses both layman’s terms and medical terminology in his explanations of anatomy, as he designed the pamphlet to give practical information about reproduction to his patients. Following a discussion of reproductive anatomy, Knowlton addresses the mechanics of the conception, including information on the stages of a woman’s menstrual cycle, ovulation, properties of semen and sperm, fertilization, and pregnancy. He mentions some signs of pregnancy, including a decrease in appetite, vomiting and nausea in the morning, heartburn, and difficulty sleeping. Knowlton notes that pregnancy cannot be confirmed until about six weeks after conception and is done via a pelvic examination that reveals the woman’s uterus has descended lower in her body than it normally sits. He states that pregnancy is typically nine months, during which the fetus grows and develops in the uterus.

In the last part of chapter two, Knowlton states that at the time physicians still did not fully understand how the sperm reached the eggs in the ovaries leading to fertilization. He cites three hypotheses for the mechanism that leads to fertilization and states that he agrees most with physician William Potts Dewees from Philadelphia, Pennsylvania. Dewees suggested that a set of vessels connected the surface of the vagina to the ovaries. During intercourse, a man’s semen was absorbed by those vessels on the surface of a woman’s vagina and allowed the sperm to flow into the fallopian tube to fertilize the woman’s egg. In a footnote from the publishers, Bradlaugh and Besant state that that view of fertilization is no longer accepted by the scientific community. Rather, they state that it has now been discovered that eggs or ova are discharged from the ovaries into the uterus during the menstrual cycle and independent of intercourse. Bradlaugh and Besant state that if intercourse and ejaculation of semen occurs when the ova is in the uterus, conception can take place.

In the third chapter of The Fruits of Philosophy, Knowlton highlights some methods of controlling and preventing conception. First, Knowlton asserts that conception will be difficult for women who do not menstruate regularly. He states that for a woman to conceive, a physician must first regulate the woman’s menstrual cycle. He then mentions that sterility can occur naturally, which he attributes to physiological inactivity and a weakness of the reproductive system. Knowlton then provides a remedy for that type of sterility: exercising in open air, eating nourishing food, wearing flannel clothing, and drinking a concoction of steel metal shavings and cider. He states that those activities heal the uterine system over the course of a few months. He includes other medical recipes for sterility such as Dewees’ Volatile Tincture of Guaiac, Gum Guaicaum, Spirits of Ammonia, and tincture of Spanish Flies, among others. Knowlton also discusses infertility and impotence among men, and often attributes it to alcohol or tobacco use, and general anxiety. Common treatments for male infertility include cold baths, cheerful company, change of scenery, regular exercise, and medical remedies such as cayenne and tincture of flies.

Knowlton goes on to discuss methods of preventing conception. First, he mentions withdrawal, or a man withdrawing his penis from a woman’s vagina before releasing any sperm. He also discusses the baudruche, also known as a condom, which covers the man’s penis and prevents both conception and venereal diseases. Knowlton argues the baudruche will likely not become popular. Then Knowlton discusses the use of a sponge moistened with water in the vagina to prevent sperm from traveling far enough to fertilize a woman’s egg. However, he argues that the ridges in the vagina could allow sperm to be dislodged when the sponge is removed, thus he does not recommend this method unless paired with some chemical liquid to destroy the sperm. He also adds that using a vaginal wash after sexual intercourse could chemically alter the sperm and prevent fertilization. For a vaginal wash, Knowlton recommends a solution of zinc, aluminum, pearl-ash, and a salt. Knowlton concludes the chapter by stating that it is important to have a safe, effective, and attainable method of contraception.

In the last chapter of the pamphlet, Knowlton discusses the reproductive instinct, which he states is the desire for sexual intercourse. He asserts that no other instinct has a greater impact on human happiness and satisfaction. However, he argues that too often the instinct is not controlled by reason and individuals act on the instinct in an improper manner. He argues that it is the duty of the physician to provide instruction in regards to the reproductive instinct, just as a physician would in regards to desires for eating, drinking, exercise, and more. He states that humans are likely to act on the instinct too early and at the wrong time, resulting in dissatisfaction within the family. He suggests that the proper age to have children is approximately seventeen years old for women and a few years older for men. He provides instances in which individuals should not gratify their sexual desires, including during menstruation because it can produce symptoms similar to syphilis and when a woman is far along in her pregnancy because it might impair the future offspring’s mental capacity. Knowlton also states that the effects of sex are much greater on men than women; he states that the male system is quickly exhausted by intercourse. He suggests that a protein rich diet will help men recover from intercourse, and a cold vegetable and milk diet will calm further sexual desires.

Knowlton concludes with a discussion of possible objections in the last section titled “Appendix.” He states that people may object to the knowledge of contraception as it may increase illegal sexual encounters such as prostitution, adultery, or intercourse outside of marriage. However, Knowlton counters by saying that prostitution occurs because there are so many young unmarried men and women. He continues by saying that young men and women don’t marry not because they don’t wish to marry young, but because they believe that when they marry they will have children and start a family. Knowlton argues that the spread of information on pregnancy prevention will lead to an increase in happy families and fewer poverty-stricken, overpopulated families.

After Besant and Bradlaugh republished Knowlton’s pamphlet, they were arrested for violating the Obscene Publications Act of 1857, which made the sale of obscene literature illegal in England. Bradlaugh and Besant were convicted and sentenced to jail. However, on appeal, their convictions were overturned. The trial of Bradlaugh and Besant was heavily publicized in the media and the number of copies of the pamphlet in circulation increased from 700 to 125,000 in the span of one year.


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  3. Knowlton, Charles. The Fruits of Philosophy: The Private Companion for Young Married People. London: James Watson, 1832.
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Claudia Nunez-Eddy

How to cite

Nunez-Eddy, Claudia, Meek, Caroline, "The Fruits of Philosophy (1832), by Charles Knowlton". Embryo Project Encyclopedia ( ). ISSN: 1940-5030


Arizona State University. School of Life Sciences. Center for Biology and Society. Embryo Project Encyclopedia.

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