We all know of the legendary Kama Sutra and its endless catalog of sexual variety. But do you know why those varieties were spelled out in such loving detail?

I just discovered this explanation, from near the end of the famous translation by Sir Richard Burton:

The chief reason for the separation between the married couple and the cause which drives the husband to the embraces of strange women, and the wife to the arms of strange men, is the want of varied pleasures and the monotony which follows possession. There is no doubt about it.

Monotony begets satiety, and satiety distaste for congress, especially in one or the other; malicious feelings are engendered, the husband or the wife yields to temptation, and the other follows, being driven by jealousy.

For it seldom happens that the two love each other equally, and in exact proportion, therefore is the one more easily seduced by passion than the other. From such separations result polygamy, adulteries, abortions, and every manner of vice, and not only do the erring husband and wife fall into the pit, but they also drag down the manes of their deceased ancestors from the place of beatified mortals, either to hell or back again upon this world.

Fully understanding the way in which such quarrels arise, I have in this book shown how the husband, by varying the enjoyment of his wife, may live with her as with thirty-two different women, ever varying the enjoyment of her, and thus rendering satiety impossible. I have also taught all manner of useful arts and mysteries, by which she can render herself pure, beautiful, and pleasing in his eyes.