Aristotle's Masterpiece, also known as The Works of Aristotle, the Famous Philosopher, is a sex manual and a midwifery book that was popular in England from the early modern period through to the nineteenth century. It was first published in 1684 and written by an unknown author who falsely claimed to be Aristotle. As a consequence the author is now described as a Pseudo-Aristotle, the collective name for unidentified authors who masqueraded as Aristotle. Some claim that the book was banned in Britain until the 1960s, although there was no provision in the UK for "banning" books as such. However, reputable publishers and booksellers might have been cautious about selling Aristotle's Masterpiece, at least in the wake of the 1857 Obscene Publications Act.

Although many people in the twenty-first century might think of early modern readers as prudish, Aristotle’s Masterpiece was not only a book on midwifery but also a sex manual. It therefore gave frank explanations of topics ranging from childbirth to "the purpose, pleasures, and particulars of sex." Also, unlike many later texts, it acknowledged women’s sexual pleasure – something that people often downplayed in later centuries after male midwives rose in popularity and open conversations about sex became less common.

Through the seventeenth and eighteenth centuries, the work was published in three different versions in 9, 20 and 78 editions respectively. The first version borrowed most of its content from two earlier works, the Secret Miracles of Nature by Levinus Lemnius and the anonymous Complete Midwives Practice Enlarged. The latter had been a successful work by itself, coming second only to Nicholas Culpeper's Directory for Midwives in number of seventeenth century editions.

A second version was released by publisher Benjamin Harris in 1697. The first half contained most of the first version and the second half was borrowed from John Sadler's A Sick Women's Private Looking-Glas (published in 1636). The third version, published around 1710, was different from the previous versions, but again copied material from other works on the subject. These included the Directory for Midwives, John Pechey's 1698 version of the Compleate Midwive's Practice Enlarged, and other popular books on sex and reproduction available at the time.

The third version was still printed and sold to a general audience in the early twentieth century. It remained unchanged from the eighteenth century editions, because the modern theory on sexuality had not yet been conceived. Because the book was based on the ancient theory of humorism, it provided some outdated information, in particular on the home remedies it prescribed.

The third version is divided into two parts. The first part covers anatomy, sexual intercourse and marriage. The second part was intended for married women and explains pregnancy and midwifery.

The first part starts with a description of the male and female sex organs in the first chapter. The second chapter advocates sexual intercourse in monogamous relationships and warns against polygamy and adultery, because both are forbidden by Christian doctrine. It finishes with an explanation of when the reproductive age begins and ends. The third chapter explores virginity. It correctly states that a torn hymen does not necessarily mean a woman is not a virgin.

The second part continues with the process of fertilisation, pregnancy, and how the sex of the fetus can be determined. The second chapter provides advice on how women can become pregnant. The third chapter describes the progress of pregnancy. Failure of the pregnancy, infertility and its causes are the subject of the fourth chapter. The part ends with a chapter on things women should do and avoid during their pregnancy.