Our views on impotence are completely bound up with the time and culture we live in. The ancient Chinese, for instance, never saw the phenomenon of impotence as a significant problem. When the penis no longer became hard enough, the method of ‘soft’ entry was recom­mended, as described by Jolan Chang in The Tao of Love and Sex. If a man is experienced and dextrous enough, according to this old Chinese method, he can manoeuvre even a completely limp penis inside a woman. According to the Tao one must not attempt penetration when the vagina is not moist. If necessary, vegetable oil can be used as a lubricant. The key to the success of this soft penetration method is the man’s dexterity. As soon as the penis has been manoeuvred into the vagina, he must make a ring round the base of the penis with his fingers with the aim of keeping the tip as stiff as possible. You might conclude that soft entry is a sensible technique for men with erection problems, but that a potent man will have no need of it. According to the Chinese tradition, however, this is definitely not true. ‘Soft entry is not just for the beginner or the problem case. It is an integral part of the Tao of Love,’ writes Jolan Chang. However, there is a snake in the grass. Soft entry and deferred ejaculation in fact serve only male self-interest. Men who want to live to a great age must according to the prescripts of the Tao replenish their weakening yang, the male essence, which is the source of strength, energy and a long life – with yin shui, the water of yin, or the vaginal secretions of young women. Because yang is essen­tial for the health and energy of the man, he must not harm it. This is why a Taoist seldom ejaculates during coitus. Instead he tries to keep his strength up with the secretions of his female partners. The more yin shui he absorbs, the more the essence of the man is strengthened, which is partly why there must be very regular intercourse!

Similarly in the ancient Hindu culture, from approximately 4000 to 1000 bc, the solution to erection problems was sought not so much in the man himself as outside him, for example in eating a mixture of sesame seed, salt, pepper, brown sugar, eggs and buttermilk. The Hindus had many remedies for impotence, which were written down in the Ayur Vedas, meaning literally: ‘Poems on the Knowledge of Life’. The best-known of these is the ‘Sushruta Samhita’. In the Indian sex manual Kama Sutra, written in ad 400, great attention is given to the dimensions of the sex organ. On the basis of penis size men are divided into hares, bulls and stallions, while women can be hinds, mares or elephants. The Kama Sutra argues that the combination of a hare-man and a hind-woman leads to better sex than the combination of either of these two with a larger animal. Anyone wishing to follow this advice, though, encounters a practical problem: how many partners do you need to experiment with before you find the right size? In ancient India weak erections or overshort penises were also tackled with an ointment made of equal parts of myrrh, arsenic, aniseed and boric acid, mixed with sesame oil.

When, many centuries later, Frederick of Prussia lay on his deathbed debilitated by disease, his personal physician prescribed the company of a young woman. However, this was not a matter of potency. The doctor assumed that the spirit of a young person could pass into an older person, causing a kind of rebirth. At the time this phenomenon was called sunamitism after the Sunamite maid of King David in the Bible.

It is said of the legendary first emperor of China, the Yellow Emperor, the patriarch of the race of Han, from whom all Chinese are supposed to be descended, that he became immortal by going to bed with a thousand young virgins. The emperors who succeeded him all believed that the more sexual partners they had the longer they would live: hence their thousands of concubines. The first emperor of the Qin dynasty, Qin Shihuuangdi is said to have sent a Taoist priest and five hundred virgins across the sea in search of the elixir of immortality. According to legend the Japanese are the descendants of this priest and the five hundred virgins on the mission.

Nowadays the view is that the invigorating effect of young people on the elderly is mainly psychological in nature. Sometimes a young woman feels attracted to an older partner, sexually as well as in other ways. That can reach the point where it could be seen as pathological: a condition that until recently psychologists described as ‘gerontophilia’.