Michel Foucault, The Will to Knowledge [La Volonte de Savoir], The History of Sexuality Vol. 1 (1990 [1976]).

Part 3: 'Scientia Sexualis'.

Until Freud at least, the discourse on sex - the discourse of scholars and theoreticians - never ceased to hide the thing it was speaking about. We could take all these things that were said, the painstaking precautions and detailed analyses, as so many procedures meant to evade the unbearable, too hazardous truth of sex. And the mere fact that one claimed to be speaking about it from the rarefied and neutral viewpoint of science is in itself significant. This was in fact a science made up of evasions since, given its inability or refusal to speak of sex itself, it concerned itself primarily with aberrations, perversions, exceptional oddities, pathological abatements, and morbid aggravations. It was by the same token a science subordinated in the main to the imperatives of a morality whose divisions it reiterated under the guise of the medical norm. Claiming to speak the truth, it stirred up people's fears; to the least oscillations of sexuality, it ascribed an imaginary dynasty of evils destined to be passed on for generations; it declared the furtive customs of the timid, and the most solitary of petty manias, dangerous for the whole society; strange pleasures, it warned, would eventually result in nothing short of death: that of individuals, generations, the species itself.

It thus became associated with an insistent and indiscreet medical practice, glibly proclaiming its aversions, quick to run to the law and public opinion, more servile with respect to the powers of order than amenable to the requirements of truth. Involuntarily naive in the best of cases, more often intentionally mendacious, in complicity with what it denounced, haughty and coquettish, it established an entire pornography of the morbid, which was characteristic of the fin de siecle society. [...] But beyond these troubled pleasures, it assumed other powers; it set itself up as the supreme authority in matters of hygenic necessity, taking up the old fears of venereal affliction and combining them with the new themes of asepsis, and the great evolutionist myths with the recent institutions of public health; it claimed to ensure the physcial vigor and the moral cleanliness of the social body; it promised to eliminate defective individuals, degenerate and bastarized populations. In the name of a biological and historical urgency, it justified the racisms of the state, which at the time were on the horizon. It grounded them in "truth".

When we compare these discourses on human sexuality with what was known at the time about the phsyiology of animal and plant reproduction, we are struck by the incongruity. Their feeble content from the standpoint of elementary rationality, not to mention scientificity, earns them a place in history apart in the history of knowledge. [...] It is as if a fundamental resistance blocked the development of a rationally formed discourse concerning human sex, its correlations, and its effects. A disparity of this sort would indicate that the aim of such a discourse was not to state the truth but to prevent its very emergence.
[...]

This much is undeniable: the learned discourse on sex that was pronounced in the nineteenth century was imbued with age-old delusions, but also with systematic blindnesses: a refusal to see and to understand; but further...a refusal concerning the very thing that was brought to light and whose formulation was urgently solicited. [...] Let Charcot's Salpetriere (http://www.indiana.edu/~intell/charcot.shtml) [French medical institute] serve as an example in this regard: it was an enormous apparatus for observation, with its examinations, interrogations, and experiments, but it was a machinery for incitement, with its public presentations, its theater of ritual crises, carefully staged with the help of ether or amyl nitrate, its interplay of dialogues, palpations, laying on of hands, postures which the doctors elicited or obliterated with a gesture or a word, its hierarchy of personnel who kept watch, orgainized, provoked, monitored, and reported, and who accumulated an immense pyramid of observations and dossiers. It is in the xontext of this continuous incitement to discourse and to truth that the real mechanisms of misunderstanding operated: thus Charcot's gesture interrupting a public consultation where it began to be too manifestly a question of "that"; and the more frequent practice of deleting from the succession of dossiers what had been said and demonstrated by the patients regarding sex, but also what had been seen, provoked, solicited by the doctors themselves, things that were almost entirely omitted from the published observations.

The unpublished documents dealing with the lessons of Charcott, which can still be found at the Salpetriere, are again more explicit on this point than the published texts. The interplay of incitement and elision is clearly evident in them. A handwritten note gives an account of the session of November 25, 1877. The subject exhibits hysterical spasms; Charcot suspends an attack by placing first his hand, then the end of a baton, on the woman's ovaries. He withdraws the baton, and there is a fresh attack, which he accelerates by administering inhalations of amyl nitrate. The afflicted woman then cries out for the sex baton in words that are devoid of any metaphor: "G. is taken away and her delirium continues."

The important thing, in this affair, is not that these men shut their eyes or stopped their ears, or that they were mistaken; it is rather that they constructed around and apropos of sex an immense apparatus for producing truth, even if this truth was to be masked at the last moment. The essential point is that sex was not only a matter of sensation and pleasure, of law and taboo, but also of truth and falsehood, that the truth of sex became something fundamental, useful, or dangerous, precious or formidable: in short, that sex was constituted as a problem of truth. What needs to be situated, therefore, is not the threshold of a new rationality whose discovery was marked by Freud - or someone else - but the progressive formation (and also the transformations) of that "interplay of truth and sex" which was bequeathed to us by the nineteenth century, and which we may have modified, but, lacking evidence to the contrary, have not rid ourselves of. Misunderstandings, avoidances, and evasions were only possible, and only had their effects, against the background of this strange endeavour: to tell the truth of sex. An endeavour that does not date from the nineteenth century, even if was then that a nascent science lent it a singular form. It was the basis of all the aberrant, naive, and cunning discourses where knowledge of sex seems to have strayed for such a long time.

Historically, there have been two great procedures for producing the truth of sex.
On the one hand, the societies - and they are numerous: China, Japan, India, Rome, the Arabo-Mulem societies - which endowed themselves with an ars erotica. In the erotic art, truth is drawn from pleasure itself, understood as a practice and accumulated as experience; pleasure is not considered in relation to an absolute law of the permitted and the forbidden, nor by reference to a criterion of utility, but first and foremost in relation to itself; it is experienced as pleasure, evaluated in terms of intensity, its specific quality, its duration, its reverberations in the body and the soul. Moreover, this knowledge must be deflected back into the sexual practice itself, in order to shape it as though from within and amplify its effects. In this way, there is formed a knowledge that must remain secret, not because of an element of infamy that might attach to its object, but because of the need to hold it in the greatest reserve, since, according to tradition, it would lose its effectiveness and its virtue by being divulged. Consequently, the relationship to the master who holds the secret is of paramount importance; only he working alone, can transmit this art in an esoteric manner and as the culmination of an initiation in which he guides the disciple's progress with unfailing skill and severity. The effects of this masterful art, which are considerably more generous than the spareness of its prescriptions would lead one to imagine, are said to transfigure the one fortunate enough to receive the privileges: an absolute mastery of the body, a singular bliss, obliviousness to time and limits, the elixir of life, the exile of death and its threats.

On the face of it at least, our civilization possesses no ars erotica. In return, it is undoubtedly the only civilization to have developed over the centuries procedures for telling the truth of sex which are geared to a form of knowledge-power strictly opposed to the art of initiations and the masterful secret: I have in mind the confession.

Since the Middle Ages at least, Western societies have established the confession as one of the main rituals we rely on for the production of truth: the codification of the sacrament of penance by the Lateran Council in 1215, with the resulting development of confessional techniques, the declining importance of accusatory procedures in criminal justice, the abandonment of tests of guilt (sworn statements, duels, judgements of God) and the development of methods of interrogation and inquest, the increased participation of the royal administration in the prosecution of infractions, at the expense of proceedings leading to private settlements, the setting up of tribunals of Inquisition: all this helped to give the confession a central role in the order of civil and religious powers. [...] For a long time, the individual was vouched for by reference to others and the demonstration of his ties to the commonweal (family, allegiance, protection); then he was authenticated by the discourse of truth he was able or obliged to pronounce concerning himself. The truthful confession was inscribed at the heart of the procedures of individualization by power.

In any case, next to the testing rituals, next to the testimony of witnesses, and the learned methods of observation and demonstration, the confession became one of the West's most hightly valued techniques for producing truth. We have become a singularly confessing society. The confession has spread its effects far and wide. It plays a part in justice, medicine, education, family relationships, and love relations, in the most ordinary affairs of life, and in the most solemn rites; one confesses one's crimes, one's sins, one's thoughts and desires, one's illnesses and troubles; one goes about telling, with the greatest precision, whatever is most difficult to tell. One confesses in public and in private, to one's parents, one's educators, one's doctor, to those one loves; one admits to oneself, in pleasure and in pain, things it would be impossible to tell to anyone else, the things people write books about. One confesses - or is forced to confess. When it is not spontaneous or dictated by some internal imperative, the confession is wrung from a person by violence or threat; it is driven from its hiding place in the soul, or extracted from the body. Since the Middle Ages, torture has accompanied it like a shadow, and supported it when it could go no further: the dark twins. The most defenseless tenderness and the bloodiest powers have a similar need of confession. Western man has become a confessing animal.

[...]
Imagine how exorbitant must have seemed the order given to all Christians at the beginning of the thirteenth century, to kneel at least once a year and confess to all their transgressions, without omitting a single one. And think of that obscure partisan, seven centuries later, who had come to join the Serbian resistance deep in the mountains; his superiors asked him to write his life story; and when he brought them a few miserable pages, scribbled in the night, they did not look at them but only said to him, "Start over, and tell the truth." Should those much discussed language taboos make us forget this millennial yoke of confession?

[b]From Christian penance to the present day, sex was a privileged theme of confession. A thing that was hidden, we are told. But what if, on the contrary, it was what, in a quite particular way, one confessed? Suppose the obligation to conceal it was but another aspect of the duty to admit to it (concealing it all the more and with greater care as the confession of it was more important, requiring a stricter ritual and promising more decisive effects)? What if sex in our society, on a scale of several centuries, was something that was placed within an unrelenting system of confession? The transformation of sex into discourse...the dissemination and reinforcement of heterogeneous sexualities, are perhaps two elements of the same deployment: they are linked together with the help of the central element of a confession that compels individuals to articulate their sexual peculiarity - no matter how extreme. In Greece, truth and sex were linked, in the form of pedagogy, by the transmission of a precious knowledge from one body to another; sex served as a medium for initiations into learning. For us, it is in the confession that truth and sex are joined, through the obligatory and exhaustive expression of an individual secret. But this time it is truth that serves as a medium for sex and its manifestations.

You definitely seem well-versed on the history of sexuality, which I am not, so there really isn't anything relevant on the subject that I can think to say except perhaps that I've always found the act of confession to create a climate of somewhat erotic secrecy when the confession you're making is sex-related. The idea that sex is something that's wrong and that it's not supposed to be spoken of except in the most hushed manner (i.e. with a priest in confession, so that whatever you divulge is shrouded with the label of sacrosanct) lends it a mystique that can't be lived up to. No sex is as bad and as dirty (in the good way) as it seems when you're confessing it to a priest.

Unless it's with a priest:)

Have to say a lot of people do disagree with Foucault's approach...some with good reason...

His argument, going on to psychology etc, is that the discourse (as part of an apparatus of power - i.e. institutions) creates its own subjects...i.e. homosexuality as a medico-scientific artefact with its related pathologies...but also heterosexuals as well...