What is your record sustained erection time in sexual intercourse? was the question put by Kinsey to several thousand American students. And what was the result? For 4 per cent it was under five minutes, for 18 per cent between about six minutes and a quarter of an hour, for 19 per cent between a quarter of an hour and half an hour, for 26 per cent between half an hour and an hour, for 14 per cent between one and two hours, for 5 per cent between two and three hours and for 4 per cent for three hours or more. Older readers will undoubtedly have to think hard, since you establish your record in your youth. Quite a few men lose their erection prematurely because they unconsciously assume the ‘onlooker’s role’. Their thoughts wander, they cease to participate in intercourse and their erection droops. In his Confessions (1781) Jean-Jacques Rousseau (1712-1778) describes such an experience, a failed adventure with the Venetian courtesan Giulietta, at length.

Full of passion, he appears at her bedside, but no sooner has he been able to see her in all her beauty than a thought arises in him that moves him to tears and completely distracts him from his original intention. He develops the thought more and more fully and his desire evaporates:

Suddenly, instead of the fire that devoured me, I felt a deathly cold flow through my veins; my legs trembled; I sat down on the point of fainting, and wept like a child.

Who could guess the cause of my tears, or the thoughts that went through my head at that moment? ‘This thing which is at my disposal’, I said to myself, ‘is nature’s masterpiece and love’s. Its mind, its body, every part is perfect. She is not only charming and beautiful, but good also and generous. Great men and princes should be her slaves. Sceptres should lie at her feet.

The adventure eventually ends in a shameful fiasco. The young Jacques notices that the courtesan has a malformed nipple. He describes it at length and, inevitably, places the responsibility for his impotence at the door of the courtesan:

I beat my brow, looked harder, and made certain that this nipple did not match the other. Then I started wondering about the reason for this malformation. I was struck by the thought that it resulted from some remarkable imperfection of Nature and, after turning this idea over in my head, I saw as clear as daylight that instead of the most charming creature I could possibly imagine, I held in my arms some kind of monster, rejected by Nature, men, and love. I carried my stupidity so far as to speak to her about her malformed nipple. First she took the matter as a joke and said and did things in her skittish humour that were enough to make me die of love. But as I still felt some remnant of uneasiness, which I could not conceal from her, I finally saw her blush, adjust her clothes, and take her place at the window, without a word.

The scene ends with the now proverbial exclamation by the disap­pointed and angry courtesan: Lascia le donne e studia la matematica! (Give up women and study mathematics!)