A woman is obviously different from a man. The anatomical difference is clear but, as well, women have a different perception of many experiences, although how much this is due to prevailing cultural attitudes and how much to gender difference is not clear. 

The anatomical differences are apparent at once, particularly in the development of a woman's breasts. Among Western communities, the breast has a unique sexual symbolism, and even if fashion diminishes its rotundity, the hemispherical mammary glands are a potent attraction for the male eye. In communities where breasts are habitually exposed, they have little sexual connotation, being considered for what they are – a source of nourishment for the infant. 

The more specific anatomical differences are of the genital organs. The male external genitals – the penis and the testicles – are absent in women, a fact which suggested to Freud that many of women's sexual problems related to an envy for the absent penis and a complex that the testicles had been castrated. Woman was therefore a mutilated male, and inferior to man. Freud was more than unfair to women, and considerably confused about them, possibly because of his own upbringing in a traditional Jewish middle-class family. He held that woman had a smaller intellectual capacity, a far greater vanity, a constitutional passivity, a weaker sexuality, and a greater disposition to neurosis. 

At the same time, he considered her enigmatic, her femininity a complicated process, her psychology involved. Studies over the past half century have shown that Freud's view of woman as an inferior, mutilated male is incorrect, and his assessment of her inferiority and her instability is more an indictment of the cultural environment in which she is brought up, than of her inherited make-up. In other words, a woman behaves in a certain way because she is brought up to believe that society expects her to behave in that way. This does not imply that she is weaker than or inferior to a man, even if both women and men are brought up by society to believe this. Indeed, longevity studies show that the female is stronger than the male, less likely to be aborted when in her mother's womb, more likely to be born alive, less likely to succumb to infection in the first years of life, and more likely to live beyond the age of 65. 

Given the opportunity, a woman can succeed in most activities as well as a man, but in one activity she is unique. The human female is a mammal. She carries her infant in the womb until it is sufficiently well developed to survive, or at least to suck; she suckles it and cares for it. This process of internal development of the infant is only possible because the womb – or uterus – is in a protected position, enclosed by the strong bones of the female pelvis. 

Although the uterus is central to the anatomical difference between male and female, the most obvious differences are those of the external genitalia, which will be described first. After that, the internal genital organs, the vagina, the uterus, the oviducts (Fallopian tubes) and the ovaries will be described, for if a woman has some idea of her anatomy, much of what follows in this book will be easily understood.