Do you believe in magic? asks the song. Their eyes met across a crowded room and: “Whoever loved that loved not at first sight?”

(Shakespeare: As You Like It) Aaah, love, that old black magic, cream in the coffee, sun, moon and stars, spine-tingling peak experience for which everyone, it seems, yearns. Love, spawner of more plush red velvet hearts, bunches of roses and posh boxes of chocolates than you can shake a stick at this Valentine’s morning: what’s it for, why do we do it? After all, for every Juliet moonily speaking her lover’s name aloud just to hear it, for every Marlene Dietrich sultrily crooning, “Falling in love again, I can’t help it”, there are Juliets stabbing themselves and South Pacific maidens washing men right out of their hair; for every fairy-tale wedding (Charles and Diana!), it seems there’s a sordid divorce just around the corner.

Yet.millions of couples throughout history have bypassed the moment of dynamite attraction and gone straight to marriage arranged by their families. Is falling in love really necessary? Or is it fancy dress for hormones, pheromones, sperm and ova?

Research by Knut Kampe, of the Institute of Cognitive Neuroscience at University College, London (published in Nature, 2001) reveals that when lovers first see each other, a reward centre in the brain lights up, networking to other pleasure sources. Production of phenylethylamine is triggered, quickening the heartbeat and moistening the palms. Loss of appetite, preoccupation, heightened senses and physical arousal follow.

Next step, passionate love-making. Further step, eternal bliss. Or so our valentines promise.

Somehow, there’s often a hitch, even if we get hitched. As Freud suggested, the erotic instinct is never fully satisfied. “Post coitum omnia animalia tristia sunt” (after intercourse all animals are sad), as the Roman poet Ovid put it. “Past reason hunted, and no sooner hadPast reason hated,” goes one Shakespearean sonnet. Physical aspects of love turn out to be a poor basis for breakfast conversation next morning, let alone lifelong partnership, whatever might be suggested in the glossy wedding magazines (Your Wedding, Brides etc are the most buoyant sector of the UK magazine market). Or love may be blind but your parents are not, as one teen website remarked recently. We are social as well as emotional beings and the biological story is only one strand in love’s narrative.

Hunger for romantic love fuels the greetings card industry, currently selling 40 cards a year for every man, woman and child in the British Isles. It keeps the diamond industry going (the first diamond engagement ring was given by Archduke Maximillian of Hamburg to Mary of Burgundy in 1477). Cosmetics, clothes, music, mirrors, hairdressers: the list of economic activities dependent on our desire to make ourselves appear lovable is well-nigh endless. In the year 2000, 305,900 marriages were registered in the UK, a drop of 25 per cent on 1976, but a 2 per cent increase on 1999, so the trend is up.

“Love and marriage, love and marriage Go together like a horse and carriage,” sang Frank Sinatra in his 1955 hit from the musical Our Town.

That was the way things were meant to be done. Yet, until recently, marriage and love have not universally been seen as inevitable bedfellows.

A quick survey of world religions makes the point.

For the Jews, romance is practical. “It is not good that the man should be alone,” God observes in the Bible (Gen 2: 18). So, God decided to create Eve for Adam: “I will make an helpmeet for him.” A practical life-partner, to prevent loneliness, work together and raise children, that was Eve’s lot. (Unfortunately, she got tempted by a smooth-talking stranger, broke her diet, went shopping for clothes and ended up in the pains of childbirth. Same old story. ) However, there are other, more lyrical and less stern depictions of sexual relations in the Hebrew Bible: the patriarch Jacob falls in love at first sight with Rachel, so much so that he works seven years for her father to win her, is fobbed off with her sister Leah and then works seven more until he is allowed to marry her. The Song of Songs is an extended erotic celebration of a woman (even if it is intended as an allegory) and one of the things that are “too wonderful” for the writer of Proverbs chapter 30 is “the way of a man with a maid”.

In the Christian tradition, the whole man-women thing appeared more problematic. Though marriage is a sacrament, St Paul was grudging in his endorsement: “To avoid fornication, let every man have his own wife, and every woman have her own husband” (I Cor 7: 2) for, “it is better to marry than to burn (in the pains of sexual frustration)” (I Cor 7: 9). Celibates stood more chance of entering the kingdom of heaven. Women, as Eve’s heirs, could be a snare and a delusion to men. Men are supposed to be the heads of households, not giddy with passion.

For Buddhists, marriage is mundane. Spiritual growth is for individuals to develop, marriage for getting along in the world. In the holy writing the Mahamangala Sutra, loving one’s spouse and children is described as one of the five things that will bring happiness and blessings in this life.

Strong feelings of any kind, though, are the cause of ignorance and suffering - this life is only a qualified good.

For Muslims, one of the hadiths (sayings) of the Prophet Mohammed sums up:

“Marriage is my sunna (edict). Whosoever keeps away from it is not from me.” Yet while celibacy is not a virtue in Islam, nor traditionally is the free choice of mates. Monogamy is preferred, but polygamy allowed as long as wives are treated equally. However, Muslims accept the laws of the country, so in the UK, polygamy is not practised. Love should follow virtue within marriage.

For Hindus, marriage lasts beyond a single life-span, and the husband and wife may switch genders through many incarnations; it is an alliance knit between individuals, families, clans and castes. Horoscopes and financial checks, the couple’s education and appearance are all weighed in the balance before a contract is made. Feelings come last. A typical blessing says: “Bounteous Indra, endow this bride with great sons and fortune. Give her 10 sons and make the husband the eleventh.” (Rig Veda X. 85. 46) The binding of young people in marriage has been accompanied by similar sentiments in numerous societies from Africa to Asia. Marriage is social cement. Romantic love, if it occurs at all, is trouble. Dowries (money settled on the bride by her family) or bride price (money paid to the bride’s parents) reflect relative bargaining power; lavish weddings establish status; and laws of inheritance and naming follow patterns of dominance. In pre-revolutionary China, girls lost all names on marriage apart from those denoting their position in the family (wife of third son, for instance). From the outside, there doesn’t seem to be much room for passion.

For Westerners, arranged marriages seem cold and calculating, like the senior Montagues and Capulets in Romeo and Juliet. Yet for many couples, their families’ involvement in their marriages is reassuring evidence of continuing care. Tragedies, such as the recent murder in Birmingham of a bride who was stabbed to death after going against the wishes of her family (though not of her father and mother), are high profile but rare; happy unions in which love grows after the wedding make no headlines. In the West, contrariwise, falling in love is seen as a normal part of growing up: counting valentines is as teenage as counting spots. It’s almost a kind of sport, favoured by some more than others, with its own patterns of behaviour, publications, spending. It’s also an aspiration, to which some sad - in both senses - individuals cannot attain.

Our obsession with romantic love has roots in the Middle Ages. Spoken French was called Romanz, as opposed to the more learned Latin; stories written in the vernacular were called “romances”. From the 12th century, the name became specific to the popular tales of chivalry and derring-do centred on King Arthur and his knights. The troubadours of Provence and France who composed these tales did their best business in courts where ladies awaited the return of their menfolk from wars, crusades and business. The flattery of the patroness became interwoven with the fervent idealism of medieval Christianity: often a beloved woman was described in terms similar to mystical visions. She was unattainable, and her lover tried to gain favour by serving her, like a feudal knight in the service of his lord. Dante is perhaps the most famous writer to use this convention - albeit for religious purposes. Although ordinary people’s lives cannot necessarily be read in works of literature, popular writing (and all the writers mentioned here were renowned throughout Europe) must reflect popular preoccupations.

As time rolled on, many of these “courtly love” romances became more secularised. Sir Thomas Malory’s Morte d’Arthur pits the base loves of the flesh (Lancelot and Guinevere) against the chaste love of God; Chaucer’s The Franklin’s Tale offers a picture of true love ending in marriage.

Petrarch’s sonnets were sensuous and earthy, while Parisian thief Francois Villon’s satirical poems were frankly salty. Still, by the time Tudor love poets such as Sir Thomas Wyatt, Sir Philip Sidney and Shakespeare appeared on the scene, there had been centuries of poets rhyming “moon” and “June”.

Even though most aristocratic marriages were arranged and most peasant ones took place well after the birth of the first healthy child, the ideal of true love, with lovers feverish, sighing and going on endlessly about their feelings had become as well established as engagement rings or dressing up to go out.

By the time of Jane Austen in the early 19th century, lovesickness and valentines were around in their present form. All her novels centre on the problems of falling in love as a precursor to marriage. What other subject is there, she would say, for those who do not wish to “dwell on misery and despair”?

Only a cynic would say that love is culturally determined, a product of leisure and individualism. What about that coup de foudre (French for both lightning-flash and falling in love)? Look at any list of ill-starred lovers, whether mythical - Hero and Leander, Orpheus and Eurydice, historical - Heloise and Abelard, Georges Sand and Chopin, Princess Margaret and Group Captain Peter Townshend, or fictional - Romeo and Juliet, Lancelot and Guinevere, the lovers in Titanic:despite forces of fate, death, social class, parents, the sea or imprisonment, these lovers are overwhelmed by the intensity of the moment. Everyone knows at least some of these tales, as well as they know their own route home. Don’t centuries of such stories carve a pattern? Aren’t our brains just waiting to flash on impact?

It’s hard to believe that our most deeply felt experiences might be just what our civilisation has formed in us. Yet, as Shakespeare had the first word, let him have the last. In the play As You Like It, Rosalind, disguised as a boy, is teasing Orlando about his passion for none other than - the fair Rosalind. He has left his valentine’s poems pinned up all over the forest. Secretly flattered, Rosalind “pretends” to be “Rosalind” so that Orlando can practise his love-arguments. Orlando says he will die if Rosalind will not have him. Rosalind ticks him off with a quick tour through the history of love.

“The poor world is almost six thousand years old, and in all this time there was not any man died in his own person, videlicet, in a love cause.

Troilus had his brains dashed out with a Grecian club, yet he did what he could to die before, and he is one of the patterns of love. Leander, he would have lived many a fair year though Hero had turned nun if it had not been for a hot midsummer night, for, good youth, he went but forth to wash him in the Hellespont and, being taken with the cramp, was drowned; and the foolish chroniclers of that age found it was Hero of Sestos. But these are all lies. Men have died, and worms have eaten them, but not for love.” Not at first sight, anyhow.

The history of Valentine’s Day

Valentine was a priest in 3rd-century Rome, beheaded at the order of Emperor Claudius II on February 14, 270, either for helping Christian prisoners escape or (less likely) for uniting young lovers in defiance of an imperial ban on marriage because it discouraged young men from joining the army. Legend has it that Valentine fell in love with a young girl in prison and sent her a note signed “from your Valentine”.

February 14 was also the eve of the Roman feast of Lupercus, the god who was supposed to keep wolves away from newborn livestock. It was customary at Lupercalia to write girls’ names on slips of paper and place these in jars. Each young man in the community drew a girl’s name from the jar; she would then be his sweetheart, at least for the feasting. Such love lotteries were banned by the early Church, but the custom persisted, becoming entwined with the sending of love messages. At medieval parties, people drew each other’s names from a bowl and pinned them on their sleeves for a week; hence the saying, “to wear your heart on your sleeve”. Poems, flowers and simple gifts such as wooden hearts (as in the song) were exchanged. The “first” valentine was sent in 1415 by Charles, Duke of Orleans, as a rhymed message to his wife while he was imprisoned in the Tower of London. Commercial valentines became available in 1800. But the roots of Valentine’s Day go yet deeper. “Sweet lovers love the spring”, as Shakespeare wrote. Many spring festivals are giddy with fertility - February 14 was the day assigned to the pairing of birds in French and English folklore; it’s the time of year when bulbs push up, lambs are born, rivers melt, windows are flung open and days get brighter.