Both ars erotica and scientia sexualis are forms of knowledge, and both deal with the imparting of secrets. The knowledge of ars erotica is a knowledge of sensual experience, a knowledge of what sexual contact feels like, and a knowledge of how to intensify one's experience of that contact. If this knowledge is contained in books, it is found in such books as The Joy of Sex or the Kama Sutra. The knowledge of scientia sexualis resembles scientific knowledge. It is intellectual rather than sensual. It concerns not one's own sexual experience, but the sexual experiences of others.
The secrets of ars erotica are like the secret recipes of a master chef. They are pieces of wisdom that must be passed on from acknowledged masters to devoted students who will put this wisdom to good use. The secrecy of ars erotica is closely tied to its sacredness, its esteemed value. The secrets of scientia sexualis are almost the opposite. Rather than being refined wisdom to be passed down from master to novice, they are base confidences to be drawn out of the novice by the master. They are secrets not because they are valuable but because they are shameful. Drawing them out becomes an act of confession.
Foucault's characterization of the modern West as being largely defined by the confession raises some interesting points. In particular, his analysis of our concept of confession as liberation, and his idea that confession has largely shaped our modern concept of the subject. Foucault has already talked about how confessions are being demanded of us by doctors, government officials, judges, teachers, parents, etc. Especially in the light of modern psychiatry and therapy, we tend to see such confessions as liberating, as therapeutic, or as lifting a weight off our shoulders. Foucault suggests that confessions are not inherently liberating, but that we have been pushed to see them that way by the powers that extract confessions from us. Because so many different groups demand confessions "for your own good," we automatically see confession as something good. Foucault implies that the idea of confession as therapeutic is not a fact, but a construction of our culture. Other cultures might think of this demand for confession as coercive rather than liberating.
This compulsion to divulge secrets about ourselves is largely responsible for our modern concept of subjecthood. Our inner life has become something to examine and to talk about. It has also become an object of knowledge and a dirty secret. The "I" that I speak about is no longer an obvious and transparent thing. It becomes a mystery even to myself, something I must dig into my own consciousness to discover. Foucault identifies this (perhaps a little hastily) with the course of modern philosophy. He might point, for instance, to Descartes' "I think therefore I am," at the source of modern philosophy; to Kant's critical philosophy, that recommends the study of our own cognitive faculties rather than abstract metaphysics; to the phenomenology or existentialism of the twentieth century that focuses on the immediacy of lived experience and consciousness. However, his analysis offers no explanation for the turn toward logic away from psychology in analytic philosophy, or the attempt by pragmatists to break down the subject/object distinction. According to Foucault, the confession has both subjected us to the powers extracting confessions and made us aware of our own subjecthood. This is what he means when he says that we have become "subjects in both senses of the word."