I am a masochist, confesses Anita Phillips. And what's more, you're probably one too. If you've ever experienced the exquisite pain of romantic love, she believes, you can't deny it. And if you haven't suffered this way, then you haven't lived

"YOU'RE A masochist, anyway," he said. It was my thirty-third birthday and two of my friends had cooked a surprise dinner for ten, with moules mariniere. But as the white wine slipped down and the dark blue shells began to collect, my friend Peter and I were already into the perennial, unwinnable argument about men and women, and which sex was the victim of the other. But a masochist? That was a new one, and especially applied to me. Nobody had ever before suggested that I might be that kind of weak, pathetic type of person. I was the kind who achieved my goals. I had published an experimental novel and was living as a freelance magazine editor. I was the heroine of every girl's own story, focused, ambitious.

So I denied the accusation and got on with the party. But it had sunk in, somehow, and from then onwards, I kept hearing that word. He runs five miles every morning? That's masochism. Do you see those shoes she's wearing, the straps that dig into her ankles? So masochistic. I hated the uptight tone, the condescension that went with it. Something was being closed off, put out of bounds.

I began to entertain the idea that maybe Peter was right. Would it really be so bad if I were a masochist? Soon, I was researching the subject in the library. And a short but intense relationship with a younger man revealed a side to my sexuality that seemed to have been waiting to come out for my entire adult life. I discovered I liked being tied up, bitten, slapped, dominated. It was more fun than anything else I'd ever done. I loved playing submissive, transgressing my own ideas of how I ought to act and what kind of treatment I should accept from a man. And I didn't feel the slightest bit demeaned by it afterwards, just the way you always do after great sex - hugely contented.

Despite living in Soho, I never became a part of the London S&M scene. Nobody I knew subscribed to Skin Two or was into bondage - or they were keeping it very quiet. And I thought of all that as a fashion thing, like being a punk, for younger people who wanted to horrify their parents or just look hip in a little rubber number.

In any case, as my dual-level research progressed I came to realise that everyone is a masochist. It isn't the property of people with pierced parts, the prima donnas of torture and mutilation, though I personally like what they do. It's an essential component of sex and love.

The masochistic aspect of attraction is that feeling of being overwhelmed by the other person. You may go wobbly or start stammering. ("He's so gorgeous! Those eyes, that voice...") ("Isn't she amazing, the way she looked when she strode across the room...") If you're holding a glass of wine, you are likely to spill it all over him or her. If you were hungry a moment ago, you aren't any longer. You may feel so peculiar that you have to make your excuses and leave, feeling an utter fool. Your clothes feel too tight, your heels catch on the edges of carpets, and nearly trip you up.

Passion, rather than action, is the prerogative of the masochist. He or she is willing to suffer for it, because that vertiginous feeling is so addictive, love is the drug. Pop music is laden with that kind of painful, troubled longing, from Marianne Faithfull's "Broken English" to French group Air's "Sexy Boy".

Anyone who hasn't experienced the feeling of being haunted by excessive desire has missed out on a hugely exciting part of romance, one that is celebrated in every love story, tragic or otherwise. In Jane Campion's film of Portrait of a Lady, Isabel Archer falls for the only man who doesn't love her, the money-obsessed, duplicitous Gilbert Osmond. Her naive, confused feelings for him are shown in a sequence of dense surrealist images that eloquently convey her loss of control.

If the result is a disastrous marriage, it was the only marriage she was prepared to make - one based on feeling, not common interests or rationality or intellectual respect. Which is why the story seems so poignant. Witnessing intense emotions or feeling them yourself is a major risk. You want to let go and enjoy the euphoria of being carried away, but the small, mean voice of prudency reminds you that it isn't in your best interests.

Masochism is the risky part of love - when you feel at a disadvantage, unsure of yourself, ready to do absolutely anything for the obscure object of desire. It's Titania in A Midsummer Night's Dream, so blinded by passion that she can't see anything wrong with her darling donkey, or Iggy Pop singing "I wanna be your dog".

Making yourself ridiculous or abject is integral. It's all about getting into the parts of yourself that are usually repressed, the disgraceful, servile, even animal aspects. The more upright and moral you are, the more you are likely to understand the attraction - and, of course, the more determined to resist it.

Both men and women are masochistic, but both sexes consider it bad publicity to admit it. Men are scared to seem effeminate, but are secretly turned on by dominatrixes. Women suspect it goes against feminist principles. Which, again, makes it perversely fascinating.

Exploring my own masochism meant I could see myself as weak and pathetic as well as focused and ambitious. I discovered that pain and pleasure aren't opposites, just different frequencies, different ways of physically responding to reality. The pain involved in masochism is highly cathartic - it cleans you out and freshens you up in a way that no amount of talking to a psychotherapist could ever do.

For me, the whole process released a lot of sexual energy, and sexual inventiveness. Paradoxically, it made me feel more on top than I ever had before. So thank you, Peter, for the birthday present. It turned out very useful.

Anita Phillips is the author of 'A Defence of Masochism', published by Faber and Faber, price pounds 9.99. Independent on Sunday readers can order copies at pounds 8.99 (inc p&p). Phone 01279 417 134, quoting this offer