what is love?

No one can live happily who has regard to himself alone and transforms everything into a question of his own utility; you must live for your neighbor, if you would live for yourself.

- Seneca

No man is an island, entire of itself; every man is a piece of the continent, a part of the main.

- John Donne

The myth of "true" love is the idea that real love burns brightly and passionately, and then it just keeps on burning until death, and then it just keeps on burning after death as the lovers are reunited in heaven. This myth seems to have grown and diffused in modern times into a set of interrelated ideas about love and marriage. As I see it, the modern myth of true love involves these beliefs: True love is passionate love that never fades; if you are in true love, you should marry that person; if love ends, you should leave that person because it was not true love; and if you can find the right person, you will have true love forever. You might not believe this myth yourself, particularly if you are older than thirty; but many young people in Western nations are raised on it, and it acts as an ideal that they unconsciously carry with them even if they scoff at it.

But if true love is defined as eternal passion, it is biologically impossible. To see this, and to save the dignity of love, you have to understand the difference between two kinds of love: passionate and companionate. According to the love researchers Ellen Berscheid and Elaine Walster, passionate love is a "wildly emotional state in which tender and sexual feelings, elation and pain, anxiety and relief, altruism and jealousy coexist in a confusion of feelings." Passionate love is the love you fall into. It is what happens when Cupid's golden arrow hits your heart, and, in an instant, the world around you is transformed. You crave union with your beloved. You want, somehow, to crawl into each other.

Berscheid and Walster define companionate love, in contrast, as "the affection we feel for those with whom our lives are deeply intertwined." Companionate love grows slowly over the years as lovers apply their attachment and caregiving systems to each other, and as they begin to rely upon, care for, and trust each other. If the metaphor for passionate love is fire, the metaphor for companionate love is vines growing, intertwining, and gradually binding two people together. The contrast of wild and calm forms of love has occurred to people in many cultures. As a woman in a hunter-gatherer tribe in Namibia put it: "When two people come together their hearts are on fire and their passion is very great. After a while, the fire cools and that's how it stays."

Passionate love is a drug. Its symptoms overlap with those of heroin (euphoric well-being, sometimes described in sexual terms) and cocaine (euphoria combined with giddiness and energy). It's no wonder: Passionate love alters the activity of several parts of the brain, including parts that are involved in the release of dopamine. Any experience that feels intensely good releases dopamine, and the dopamine link is crucial here because drugs that artificially raise dopamine levels, as do heroin and cocaine, put you at risk of addiction. If you take cocaine once a month, you won't become addicted, but if you take it every day, you will. No drug can keep you continuously high. The brain reacts to a chronic surplus of dopamine, develops neurochemical reactions that oppose it, and restores its own equilibrium. At that point, tolerance has set in, and when the drug is withdrawn, the brain is unbalanced in the opposite direction: pain, lethargy, and despair follow withdrawal from cocaine or from passionate love.

So if passionate love is a drug—literally a drug—it has to wear off eventually. Nobody can stay high forever (although if you find passionate love in a long-distance relationship, it's like taking cocaine once a month; the drug can retain its potency because of your suffering between doses). If passionate love is allowed to run its joyous course, there must come a day when it weakens. One of the lovers usually feels the change first. It's like waking up from a shared dream to see your sleeping partner drooling. In those moments of returning sanity, the lover may see flaws and defects to which she was blind before. The beloved falls off the pedestal, and then, because our minds are so sensitive to changes, her change in feeling can take on exaggerated importance. "Oh, my God," she thinks, "the magic has worn off—I'm not in love with him anymore." If she subscribes to the myth of true love, she might even consider breaking up with him. After all, if the magic ended, it can't be true love. But if she does end the relationship, she might be making a mistake.

Passionate love does not turn into companionate love. Passionate love and companionate love are two separate processes, and they have different time courses. Their diverging paths produce two danger points, two places where many people make grave mistakes. In figure below, I've drawn out how the intensity of passionate and companionate love might vary in one person's relationship over the course of six months. Passionate love ignites, it burns, and it can reach its maximum temperature within days. During its weeks or months of madness, lovers can't help but think about marriage, and often they talk about it, too. Sometimes they even commit to marriage. This is often a mistake. Nobody can think straight when high on passionate love. The rider is as besotted as the elephant. People are not allowed to sign contracts when they are drunk, and I sometimes wish we could prevent people from proposing marriage when they are high on passionate love because once a marriage proposal is accepted, families are notified, and a date is set, it's very hard to stop the train. The drug is likely to wear off at some point during the stressful wedding planning phase, and many of these couples will walk down the aisle with doubt in their hearts and divorce in their future.

The other danger point is the day the drug weakens its grip. Passionate love doesn't end on that day, but the crazy and obsessional high period does. The rider regains his senses and can, for the first time, assess where the elephant has taken them. Breakups often happen at this point, and for many couples that's a good thing. Cupid is usually portrayed as an impish fellow because he's so fond of joining together the most inappropriate couples. But sometimes breaking up is premature because if the lovers had stuck it out, if they had given companionate love a chance to grow, they might have found true love.

True love exists, I believe, but it is not—cannot be—passion that lasts forever. True love, the love that undergirds strong marriages, is simply strong companionate love, with some added passion, between two people who are firmly committed to each other. Companionate love looks weak in the graph above because it can never attain the intensity of passionate love. But if we change the time scale from six months to sixty years, as in the next figure, it is passionate love that seems trivial—a flash in the pan— while companionate love can last a lifetime. When we admire a couple still in love on their fiftieth anniversary; it is this blend of loves—mostly companionate—that we are admiring.

- Johnathan Haidt