Sexual desire declines after four to seven years. That's been proven.

The social problem is that we haven't come up with any alternative models. Our culture hasn't developed an ars erotica. Think, for example, of conditions in India or in Japanese culture and of how the erotic has been cultivated there. They're not as clinical and rabbit-like as we are.

Key feature of sexual revolution is the large-scale publication and commercialization of details that were once secret. Sexuality has been trivialized. The interesting thing about this is that exaggerated portrayals apparently destroy desire more effectively than any repression.

Fantasies have to remain dirty. Cleanliness, scrupulousness and rationality are poison for eroticism.

The sexual revolution produced cultural convulsions that were unparalleled in the 20th century. The female sex was historically sexualized and required to have orgasms for the first time. Sexual "deviants," particularly homosexuals, achieved partial emancipation.

There are many options in a marriage. If the couple has been together for a certain amount of time and has a certain amount of liberalism or life experience, it could be the kind of relationship in which one partner ventures into the occasional affair, which is then forgiven. This only happens every 13 years on average, but it obviously does occur.

Some 95 percent of all sexual contact still occurs in permanent relationships. That's an impressive number.