Lovers exchange them. Photographers stage them. Italians eat them. Rodin sculpted a naked couple sharing one. There was even a conference in London this month about the role of the kiss in history, with discussions of its place in art and culture from Graeco-Roman antiquity to Paris in the 1950s.
A slight subject, at first sight, for a serious academic conference? Not according to the organisers, who describe the kiss as "a capacious carrier of much social, political and cultural freight". A kiss, in other words, is more than just a kiss. It consists, in Freud's passion-killing formulation, of the "sexual use of the mucous membranes of the lips and mouth".
But if sex is the first connection that comes to mind when considering the kiss, it is far from being the only one. The programme for the conference, organised by Royal Holloway's Bedford Centre for the History of Women, points out that it ranges from "the stylised performative gesture to the ordinary ingredient of daily conversation" - from stage kisses to perfunctory ones, from politicians kissing babies to a peck on the cheek between friends.
But wait a minute. How many of us have actually witnessed a parliamentary candidate kissing a passing infant? Did Nelson really say "Kiss me, Hardy" as he lay dying? Other theories about kissing claim it is such an intimate act that prostitutes never allow clients to kiss them, but no one ever quotes an identifiable source for this piece of wisdom.
Kissing is so embedded in everyday life, whether in the form of a passionate embrace or an affectionate salutation, that myths have grown up around it and exist, for the most part, unchallenged.
The conference set out to examine some of these meanings. There were discussions of the dying kiss in the trenches of the first World War, the kiss of peace in early modern religion, the kiss of life in 18th-century resuscitation.
That such attention is being paid to an apparently spontaneous gesture is a step in deconstructing it, for one of the most striking things about the kiss is how often it is anything but impulsive.
The most famous images, such as Robert D'Oisneau's photograph of lovers kissing outside the Hotel de Ville in Paris, often turn out to have been staged. In spite of the woman's apparent oblivion to anything but her boyfriend's passion, they were in fact actors who spent hours under D'Oisneau's direction.
Another celebrated kiss, when Britain's Prince Charles embraced his bride on a balcony at Buckingham Palace, travelled around the world on television screens and was reproduced in millions of newspapers and magazines. Yet this picture, which all but cynics and republicans read at the time as a pure expression of romantic love, has now come to represent a very different kind of kiss, that of betrayal.
It is quite likely that both readings are wrong, in the sense that Diana was trying to inhabit a fairy tale and her spouse simply going along with what was required of him; royalty is a species of performance, staged for the masses, and Charles's kiss may have been no more insincere than Queen Elizabeth's small talk at official ceremonies and garden parties.
But the notion of the Judas kiss, the embrace offered with an evil motive, remains powerful. A Kiss Before Dying, Kiss Me Deadly, Kiss of the Vampire, Kiss of Death, Kiss Tomorrow Good- bye and Kiss Me, Kill Me are just a few of the movie titles that explicitly link intimacy, deception and danger.
This is because the kiss is an intimate gesture involving two people whose actions may mimic each other while their intent is very different. It is an unspoken transaction, fraught with opportunities for bad faith and misunderstanding: it may mean anything from "Hello" to "I love you", from "I quite fancy you" to "I would like to have passionate sex with you this instant".
Although the distinction between a peck on the cheek and a kiss with erotic intention may seem obvious, the taboo on certain kinds of kissing suggests the opposite, at least in the eyes of some observers.
"The kiss of friendship between men is strictly avoided as inclining towards the sin regarded in England as more abominable than any other," a German travel guide advised in 1819.
A recent NOP poll suggests that homophobia is as rampant as ever in Britain, and there is nothing to suggest things are much different here: 62 per cent of the men questioned said they would be terrified of being labelled gay if they gave another man a kiss or accepted one from him, while 53 per cent of Yorkshiremen said they would hit a man who tried to kiss them.
When Prince Charles greeted his brother Andrew with a kiss at Ascot two years ago, it was unusual enough to cause speculation, though not about his sexuality. Commentators wondered whether it marked a relaxation in royal mores, a perfect example of the weight of meaning attached to this simple act.
Another is the fear, sometimes expressed by pubescent girls who have not received sex education, that kissing can lead to pregnancy. If discussions of kissing almost always lead back to sexuality, it is no accident, for the mouth is a potent vehicle of desire, even if what it is seeking is not always obvious.
Naturally it represents appetite, in the sense of being the organ that ingests food, but it is more complicated than that. In the language of romance, kisses are often hungry or greedy, as though one person (usually the man) is intent on devouring the other.
KISSINg as a form of insatiable hunger is the theme of Roman writer Catullus's famous poem, in which he demands hundreds, then thousands, of kisses from his lover. The image becomes positively cannibalistic in Under The Jaguar Sun, where Italo Calvino's lovers kiss with the intensity of "serpents concentrated in the ecstasy of swallowing each other in turn".
These are potent images, confusing and conflating two pleasures, sex and eating, in a way that supports Freud's characterisation of kissing as an unconscious repetition of infantile delight in feeding.
"No one who has seen a baby sinking back satiated from the breast and falling asleep with flushed cheeks and a blissful smile can escape the reflection that this picture persists as a prototype of the expression of sexual satisfaction in later life," he wrote in Three Essays on Sexuality.
In infancy, the flow is one-way, which is a significant difference between a child ingesting milk and two adults kissing; it may explain not only the intensity of the adult experience, but the unconscious fears that seem to accompany it.
It is clearly right to view the mouth-on-mouth kiss not just as a preliminary to genital sex but as an erotic end in itself. If it wasn't, people would not have expended so much energy on banning it in public places, setting limits to how it could be shown in movies, painting it on Greek vases and writing poems about it.
No wonder a friend of mine insists that those delicious Italian confections named after kisses (baci) are really chocolate orgasms.
