Broad-minded though we take ourselves to be, lust gets a bad press. It is the fly in the ointment, the black sheep of the family, the ill-bred, trashy cousin of upstanding members like love and friendship. It lives on the wrong side of the tracks, lumbers around elbowing its way into too much of our lives, and blushes when it comes into company.
Some people like things a little on the trashy side. But not most of us, most of the time. We smile at lovers holding hands in the park, but wrinkle our noses if we find them acting out their lust under the bushes. Love receives the world's applause. Lust is furtive, ashamed, embarrassed. Love pursues the good of the other with self-control, reason and patience. Lust pursues its own gratification, headlong, impatient of any control, immune to reason. Love thrives on candlelight and conversation. Lust is equally happy in a doorway or in a taxi, and its conversation is made of animal grunts and cries. Love is individual: there is only the unique Other. Lust takes what comes. Lovers gaze into each other's eyes. Lust looks sideways, inventing deceits, stratagems and seductions, sizing up opportunities. Love grows with knowledge and time, courtship, truth and trust. Lust is a trail of clothing in the hallway, the collision of two football packs. Love lasts, lust cloys.
Lust subverts propriety. It stole Anna Karenina from her husband and son, and Vronsky from his honourable career. Living with lust is like living shackled to a lunatic. In Schopenhauer's splendid words, almost prophesying the Clinton presidency, lust
is the ultimate goal of almost all human endeavour, exerts an adverse influence on the most important affairs, interrupts the most serious business at any hour, sometimes for a while confuses even the greatest minds, does not hesitate with its trumpery to disrupt the negotiations of statesmen and the research of scholars, has the knack of slipping its love letters and ringlets even into ministerial portfolios and philosophical manuscripts.
So it might seem quixotic or paradoxical, or even indecent, to try and speak up for lust. The philosopher David Hume wrote that a virtue was any quality of mind "useful or agreeable to the person himself or to others". Lust has a good claim to qualify. Indeed, that understates it because lust is not merely useful but essential. We would none of us be here without it. So the task I set myself is to clean off some of the mud, to rescue it from the echoing denunciations of old men of the deserts, to deliver it from the pallid and envious confessors of Rome and the disgust of the Renaissance, to destroy the stocks and pillories of the Puritans, to separate it from other things that we know drag it down (for there are worse things than lust, things that make pure lust itself impure), and so to lift it from the category of sin to that of virtue. Do I really want to draw aside the curtains and let light disperse the decent night that thankfully veils our embarrassments? Am I to stand alongside the philosopher Crates the Cynic, who, believing that nothing is shameful, copulated openly in public with his wife Hipparchia? Certainly not, but part of the task is to know why not.
Some might deny that there is any task left to accomplish. We are emancipated, they say. We live in a healthy, if sexualised, culture. We affirm life and all its processes. We have already shaken off prudery and embarrassment. Sex is no longer shameful. Our attitudes are fine. So why worry?
I find myself at one with many feminists in thinking this cheery complacency odious, and not just because the expressions of a sexualised culture are all too often dehumanising, to men and especially to women, and even to children.
The sexualisation of our commercial culture is only a fascination with something that we fear or find problematic. When I lived in North Carolina, two- and three-year-old girls were usually made to wear bikini tops on the beach, and a six-year-old was banned from school because he attempted to kiss a fellow pupil. In states such as Georgia and Alabama, at least until recently, "any device designed or marketed as useful primarily for the stimulation of human genital organs" was regarded as obscene; possession, sale, purchase and so on were aggravated misdemeanours punishable by heavy fines and even prison. (England is not much better: girls can legally have sex at 16, but cannot buy vibrators until they are 18.) Like England, nearly all US states deny prostitutes anything like adequate legal protection, in spite of the overwhelming social ills that the prohibition creates.
In May 2002, advised by John Klink, sometime strategist for the Holy See, the Bush administration refused to sign a United Nations declaration on children's rights unless the UN's plans for sex and health education in the developing world were changed to teach that only sexual abstinence is permissible before marriage.
Within the US, the federal government spends about $1m (£574,000) of taxpayers' money annually on abstinence-only programmes of sex education, even though such programmes increase young people's health risks by making furtive and unprotected copulations their only option. Human Rights Watch has issued a report which says that abstinence-only programmes pose a threat to teenagers' health because information they need is denied to them in schools. A quote from a Texas teacher introduces the report: "Before [the abstinence-only programme] I could say, 'If you're not having sex, that's great. If you are, you need to be careful and use condoms.' Boy, that went out of the window." The report notes that federal programmes often lie to children, for example about the efficacy of condoms. This is not the sign of a culture that has its attitudes to sexuality under control. Similarly in the United Kingdom, the Church of England is tearing itself apart over two issues. One is that of gay priests, and the other of women bishops. This, too, is not the sign of a culture in which sex is understood as it might be. So there is work to do.
What a culture makes of "masculinity" or "femininity" spills into every corner of life. It determines how we grow up, what we become proud of and, therefore, what we are ashamed of or hostile towards. Our anxieties produce fantasies and distortion, aggression and ambition, violence and war. Fascism was perhaps the most obvious political movement that clustered around ideals of the Male, but it will not be the last. Islam's attitude to women, and to western women, need only be mentioned.
The landscape of human lust and human thinking is huge. People have devoted lifetimes to charting small parts of it. Even as you read, neurologists are plotting it, pharmacists are designing drugs to modify it, doctors are tinkering with its malfunctions, social psychologists are setting questionnaires about it, evolutionary psychologists are dreaming up theories of its origins, postmodernists are deconstructing it, and feminists are worrying about it. And a large part of the world's literature is devoted to it, or to its close relative, erotic love.
But the word lust has wider application than simply sexual desire: lust for life, lust for gold, lust for power. Perhaps sexual desire should be recognised as just one kind of desire among others. Saint Thomas Aquinas put to himself the objection that lust was not confined to sexual (venereal) matters:
It would seem that the matter of lust is not only venereal desires and pleasures. For Augustine says (Confessions ii, 6) that "lust affects to be called surfeit and abundance". But surfeit regards meat and drink, while abundance refers to riches. Therefore lust is not properly about venereal desires and pleasures.
He also worried that lust had been defined by previous authority as "the desire of wanton pleasure". But then wanton pleasure regards not only venereal matters but also many others. Therefore lust is not only about venereal desires and pleasures.
Aquinas was right to worry about getting this part of the subject straight. In many lists of the Seven Deadly Sins, lust is replaced by luxuria or luxury. This is not an innocent mistake, but reflects the urge to inject something morally obnoxious into the definition. If we associate lust with excess and surfeit, then its case is already lost. But it is a cheap victory: excessive desire is bad because it is excessive, not because it is desire. If we build the notion of excess into the definition, the desire is damned simply by its name. And the notion of excess is certainly in the wings. If we say that someone has a lust for gold, we imply more than that he simply wants money, like the rest of us. It is not just that gold puts a gleam into his eye, it is that nothing else does, or gold puts too bright a gleam.
There are many dimensions of excess. A desire might be excessive in its intensity if, instead of merely wanting something, we are too preoccupied by it or are unduly upset by not getting it. Alternatively, a desire might be excessive in its scope, as when someone wants not just power, but complete power, or not just gold, but all the gold. Sexual desire could be excessive in either way. It might preoccupy someone too much, and it might ask for too much. Don Juan illustrates both the fault of excessive preoccupation and that of encompassing too many objects. Yet many men might be hard put to know whether they differ from him in both ways, or only in one. Bill Clinton is reported to have gone into therapy in order to "cure" him of his sexual "addiction", yet the problem on the face of it (if that is the right expression) was not with the intensity of his desire but with its wayward direction and his limp self-control. And why did these minor faults, a subject of mirth in the rest of the world, arouse such obsessive hostility in conservative America? After all, it has long been known that more prostitutes fly into towns hosting Republican conventions than Democratic ones. Perhaps this sector of the American public does not like to think of its president, its God of War, stretched out in post-coital slump, victim of the calmly triumphant Venus, and with his weapons demoted to mere playthings.
It seems, if we talk of excess, that we ought to be able to contrast it with some idea of a just and proportionate sexuality; one that has an appropriate intensity, short of obsession but more than indifference, and directed at an appropriate object. People manage that, sometimes. Indeed, in one respect nature manages it for us, since eventually we calm down and go to sleep. So it would seem wrong to say that lust is in and of itself excessive. Indeed, when we are listless or depressed, or old and tired, we suffer from too little lust, not too much. And judging from our actual choices rather than our moralising, we like lust well enough. Advertising agencies fall over themselves to suggest that their products enable us to excite lust in others, but nobody ever made a fortune from prescribing ways of making ourselves repulsive.
There is another way in which lust might seem in and of itself excessive, admitting of no moderation. Eating relieves our desire for food, our hunger. And we combine it with other activities, such as talking or reading or watching television. But the activity that relieves our lust typically blocks out other functions. It doesn't literally make us blind, even temporarily, and we would be quick to desist if the wrong visitor arrived. But it is as close to ecstasy - to standing outside ourselves - as many of us get. As the body becomes flooded with desire, and still more as climax approaches, much of the world is blotted out. The brain requires a lot of blood - hence the saying that men have two organs that require a lot of blood, but only enough for one at a time. There is a literal truth here, and not only about men, which is that sexual climax drives out thought. It even drives out prayer, which is part of the church's complaint against it.
Perhaps it does not have to be like that: there are records of Chinese voluptuaries who could dictate letters while coupled to their partners. That is certainly virtuoso, but deficient in at least one of the pleasures of exercising lust, which is the abandonment itself.
It is a good thing if the earth moves. There is no such thing as a decorous or controlled ecstasy, so we should not persecute lust simply because of its issue in extremes of abandon. Indeed, such experiences are usually thought to be one of life's greatest goods, and a yardstick for others. Even in the rigid atmosphere of Catholic sanctity, the best that mystics could do to express their ecstatic communion with God or Christ was to model it upon sexual ecstasy. The metaphors are the same: in the ecstatic communion the subject surrenders, burns, loses herself, is made blind or even temporarily destroyed, suffering a "little death". Saint Teresa of Avila talks of an "arrow driven into the very depths of the entrails and the heart", so that the soul does not "know either what is the matter with it or what it desires", and still more she talks of the experience as a distress, but one "so delectable that life holds no delight that can give greater satisfaction". So it was not only Bernini who was driven to depict her in terms of orgasm. Her contemporaries were also hard put to know whether this was the work of God or the devil, and it was a close call when they finally decided on the former.
The interesting thing is the association of such a state with communion and knowledge. (Think of the biblical equation of having sex with someone and knowing them.) Hard-nosed philosophers are apt to look askance at incommunicable knowledge, and as the mystic's claim to know something that the rest of us do not seems unverifiable, it is easy to remain sceptical. However sensible it may be in the case of divine ecstasy, it is harder to dismiss the association in the case of sexual ecstasy. Are all experiences of sexual communion, of a fusion of persons, to be dismissed?
Let's return to Aquinas's own, scarcely reassuring, answer to the problem of definition.
As Isidore says, ". . . a lustful man is one who is debauched with pleasures". Now venereal pleasures above all debauch a man's mind. Therefore lust is especially concerned with such like pleasures.
The first objection to this is that it seems wrong to say that a lustful man is one who is debauched with pleasure: he may or may not be, depending on his luck. And in any case, sexual desire is rather more acute just when we are not debauched with pleasure. A sated man or woman is no longer lustful. And then the word "debauch" is scarcely neutral, implying riot and ruin. Finally, it is not true that venereal pleasures debauch a man's mind. Newton seems to have been fairly ascetic, but Einstein was certainly not.
So we must not allow the critics of lust to intrude the notion of excess, just like that. We should no more criticise lust because it can get out of hand than we criticise hunger because it can lead to gluttony, or thirst because it can lead to drunkenness.
Simon Blackburn is professor of philosophy at Cambridge University. This is an edited extract from his book Lust, part of a series of essays on the Seven Deadly Sins, which will be published next year by Oxford University Press