There are two things that can’t be described and one of them is a sunset. So runs the old school wisdom about orgasm, yet today it is difficult to escape from detailed descriptions, images and instructions about sexual climax. TV programmes such as Sex Inspectors give meticulous and graphic advice to contestants about orgasm, and few sex scenes in the movies are complete without one.

This multiplication of images suggests that orgasms have lost the cultural taboo that they once had. But if we think of the many representations, we notice a curious detail. Where female orgasms are represented with little timidity, male orgasm is rarely shown outside pornography. The female orgasm was once held to be a great enigma — and unravelled only by the sexologists of the 20th century — but the man’s climax seems desperately uninteresting. Is that because there is so little mystery about it?

The vast market for drugs that promote potency suggests the opposite, and this brings us to the real mystery of the orgasm. The key lies in the simple observation that sexual climax so frequently eludes our conscious knowledge. Why does it happen when it does? Why does it not happen when most expected or desired?

Why does it fail at times to obey any law beyond its own caprice? The very fact that sexual climax often fails to coincide with our conscious volition makes it somehow separate from us. This is made all the more opaque when an orgasm is interpreted as the entrance to a private world. When a couple make love, an orgasm can certainly be experienced as a moment of unity, but equally as a moment of separation where each party is plunged into his or her own solitude. When people discuss sex, they don’t ask “Who makes you come?”, but “What makes you come?”, implying that it isn’t an individual but something impersonal, like a fantasy, a situation or a sexual position. And so the intense sexual pleasure of one person may be felt by the other party as something selfish.

This is made more difficult for the man in that the usual sequel to his climax is the loss of his erection. Detumescence may spark a subliminal anxiety and it has been argued several times that the reason men fall asleep so swiftly after coming is to avoid this uneasiness. Men often speak of a sense of unfinished business after an orgasm, of a vague dissatisfaction.

Orgasm may involve a shared pleasure, but as an individual experience it always carries the threat of separation. It shows the strange self-sufficiency of each person, even if they require their partner to let them access this. Hence the fascination with orgasm: it has to be pinned down, seen, described, represented. Isn’t it one of the tasks of a relationship to learn to appreciate the value of someone else’s enjoyment while knowing that one can’t always be the master of it?

Darian Leader is a psychoanalyst and author