I'm dead serious: The Buddha literally advised married couples to buy property insurance.

Not quite as exciting a path as parting the veil of illusion and standing on the shimmering threshold of untarnished perfection, now is it? But as far as the Buddha was concerned, enlightenment was simply not available to householders. In this way, again, he resembled the early Christian fathers, who believed that spousal attachment was nothing but an obstacle to heaven--which does lead one to start pondering exactly what these enlightened beings had against couplehood anyhow. Why all the hostility toward romantic and sexual union, or even toward steadfast marriage? Why all the resistance to love? Or perhaps it wasn't love that was the problem; Jesus and the Buddha were the greatest teachers of love and compassion the world has ever seen. Perhaps it was the attendant danger of desire that caused these masters to worry for people's souls and sanity and equilibrium.

The problem is that we're all full of desire; it is the very hallmark of our emotional existence, and it can lead to our downfall--and to the downfall of others. In the most famous treatise on desire ever written, The Symposium, Plato describes a famous dinner party during which the playwright Aristophanes lays out the mythical story of why we humans have such deep longings for union with each other, and why our acts of union can sometimes be so unsatisfying and even destructive.

Once upon a time, Aristophanes relates, there were gods in the heavens and humans down on earth. But we humans did not look the way we look today. Instead, we each had two heads and four legs and four arms--a perfect melding, in other words, of two people joined together, seamlessly united into one being. We came in three different possible gender or sexual variations: male/female meldings, male/male meldings, and female/female meldings, depending on what suited each creature the best. Since we each had the perfect partner sewn into the very fabric of our being, we were all happy. Thus, all of us double-headed, eight-limbed, perfectly contented creatures moved across the earth much the same way that the planets travel through the heavens--dreamily, orderly, smoothly. We lacked for nothing; we had no unmet needs; we wanted nobody. There was no strife and no chaos. We were whole.

But in our wholeness, we became overly proud. In our pride, we neglected to worship the gods. The mighty Zeus punished us for our neglect by cutting all the double-headed, eight-limbed, perfectly contented humans in half, thereby creating a world of cruelly severed one-headed, two-armed, two-legged miserable creatures. In this moment of mass amputation, Zeus inflicted on mankind that most painful of human conditions: the dull and constant sense that we are not quite whole. For the rest of time, humans would be born sensing that there was some missing part--a lost half, which we love almost more than we love ourselves--and that this missing part was out there someplace, spinning through the universe in the form of another person. We would also be born believing that if only we searched relentlessly enough, we might someday find that vanished half, that other soul. Through union with the other, we would recomplete our original form, never to experience loneliness again.

This is the singular fantasy of human intimacy: that one plus one will somehow, someday, equal one.

But Aristophanes warned that this dream of completion-through-love is impossible. We are too broken as a species to ever entirely mend through simple union. The original cleaved halves of the severed eight-limbed humans were far too scattered for any of us to ever find our missing halves again. Sexual union can make a person feel completed and sated for a while (Aristophanes surmised that Zeus had given humans the gift of orgasm out of pity, specifically so that we could feel temporarily melded again, and would not die of depression and despair), but eventually, one way or another, we will all be left alone with ourselves in the end. So the loneliness continues, which causes us to mate with the wrong people over and over again, seeking perfected union. We may even believe at times that we have found our other half, but it's more likely that all we've found is somebody else who is searching for his other half--somebody who is equally desperate to believe that he has found that completion in us.

This is how infatuation begins. And infatuation is the most perilous aspect of human desire. Infatuation leads to what psychologists call "intrusive thinking"--that famously distracted state in which you cannot concentrate on anything other than the object of your obsession. Once infatuation strikes, all else--jobs, relationships, responsibilities, food, sleep, work--falls by the wayside as you nurse fantasies about your dearest one that quickly become repetitive, invasive, and all-consuming. Infatuation alters your brain chemistry, as though you were dousing yourself with opiates and stimulants. The brain scans and mood swings of an infatuated lover, scientists have recently discovered, look remarkably similar to the brain scans and mood swings of a cocaine addict--and not surprisingly, as it turns out, because infatuation is an addiction, with measurable chemical effects on the brain. As the anthropologist and infatuation expert Dr. Helen Fisher has explained, infatuated lovers, just like any junkie, "will go to unhealthy, humiliating, and even physically dangerous lengths to procure their narcotic."

Nowhere is that drug stronger than at the very beginning of a passionate relationship.

Fisher has noted that an awful lot of babies are conceived during the first six months of a love story, a fact that I find really noteworthy. Hypnotic obsession can lead to a sense of euphoric abandon, and euphoric abandon is the very best way to find yourself accidentally pregnant. Some anthropologists argue, in fact, that the human species needs infatuation as a reproductive tool in order to keep us reckless enough to risk the hazards of pregnancy so that we can constantly replenish our ranks.

Fisher's research has also shown that people are far more susceptible to infatuation when they are going through delicate or vulnerable times in their lives. The more unsettled and unbalanced we feel, the more quickly and recklessly we are likely fall in love. This makes infatuation start to sound like a dormant virus, lying in wait, ever ready to attack our weakened emotional immune systems. College students, for instance--away from home for the first time, uncertain, lacking familiar support networks--are notoriously susceptible to infatuation. And we all know that travelers in foreign lands often fall wildly in love, overnight it seems, with total strangers. In the flux and thrill of travel, our protective mechanisms break down quickly. This is marvelous in one way (for the rest of my life I will always feel a shiver of pleasure whenever I remember kissing that guy outside the bus terminal in Madrid), but it is wise in such circumstances to heed the advice of the venerable North American philosopher Pamela Anderson: "Never get married on vacation."

Anybody going through a difficult time emotionally--due to the death of a family member, perhaps, or the loss of a job--is also susceptible to unstable love. The sick and the wounded and the frightened are famously vulnerable to sudden love, too--which helps explain why so many battle-torn soldiers marry their nurses. Spouses with relationships in crisis are also prime candidates for infatuation with a new lover, as I can personally attest from the mad commotion that surrounded the end of my own first marriage--when I had the good, solid judgment to go out in the world and fall quite insanely in love with another man at the very same moment as I was leaving my husband. My great unhappiness and my shredded sense of self made me ripe for the plucking of infatuation, and boy, did I get plucked. In my situation (and from what I know now, it is a tediously common textbook example), my new love interest seemed to have a giant EXIT sign hanging over his head--and I dived right through that exit, using the love affair as an excuse to escape my collapsing marriage, then claiming with an almost hysterical certainty that this person was everything I truly needed in life.

Shocking how that didn't work out.

The problem with infatuation, of course, is that it's a mirage, a trick of the eye--indeed, a trick of the endocrine system. Infatuation is not quite the same thing as love; it's more like love's shady second cousin who's always borrowing money and can't hold down a job. When you become infatuated with somebody, you're not really looking at that person; you're just captivated by your own reflection, intoxicated by a dream of completion that you have projected on a virtual stranger. We tend, in such a state, to decide all sorts of spectacular things about our lovers that may or may not be true. We perceive something almost divine in our beloved, even if our friends and family might not get it. One man's Venus is another man's bimbo, after all, and somebody else might easily consider your personal Adonis to be a flat-out boring little loser.

Of course all lovers do--and should--see their partners through generous eyes. It's natural, even appropriate, to exaggerate somewhat our partners' virtues. Carl Jung suggested that the first six months of most love stories is a period of pure projection for just about anyone. But infatuation is projection run off the rails. An infatuation-based affair is a sanity-free zone, where misconception has no limits and where perspective finds no foothold. Freud defined infatuation pithily as "the overvaluation of the object," and Goethe put it even better: "When two people are really happy about one another, one can generally assume they are mistaken." (By the way, poor Goethe! Not even he was immune to infatuation, not for all his wisdom or experience. That staunch old German, at the age of seventy-one, fell passionately in love with the utterly inappropriate Ulrike, a nineteen-year-old beauty who turned down his heated marriage proposals, leaving the aging genius so bereft that he wrote a requiem to his own life, concluding with the lines

"I have lost the whole world, I have lost myself.") Any actual relating is impossible during such a state of pitched fever. Real, sane, mature love--the kind that pays the mortgage year after year and picks up the kids after school--is not based on infatuation but on affection and respect. And the word "respect," from the Latin respicere ( " to gaze at"), suggests that you can actually see the person who is standing next to you, something you absolutely cannot do from within the swirling mists of romantic delusion. Reality exits the stage the moment that infatuation enters, and we might soon find ourselves doing all sorts of crazy things that we would never have considered doing in a sane state. For instance, we might find ourselves sitting down one day to write a passionate e-mail to a sixteen-year-old monk in Laos--or whatever. When the dust has settled years later, we might ask ourselves, "What was I thinking?" and the answer is usually: You weren't.

Psychologists call that state of deluded madness "narcissistic love."