What do these ghosts want with me? Or rather, what do I want with them?

I am being haunted again. The last time I was haunted it was my father who was doing it. I know, I know, you've read the play. "My father - methinks I see my father." At which you're meant to come over all agitated and ask, "Where, my lord?" Then I say, "In my mind's eye, Horatio". And you think, "Have I got a surprise for you!"

Unlike Hamlet's, my father never did anything so gross as to show up in body. But it would still be wrong to think of "the mind's eye" as a place of intangible fancy. I really did see him, much in the way that, after walking into a door or coming up suddenly from a crouching to a standing position, you see stars. Little white dots which never quite arranged themselves into his features but spoke with his voice.

Maybe I was suffering emotional concussion. He talked to me, whatever the explanation. More in fact than he had ever talked to me in life. Nothing special. No messages. No grief, though he had resented his going. No histrionics about his unhous'led state. And definitely no accusations against any of my uncles. Just an easy companionableness. "Hello, what are you up to today?" That sort of thing. Then, after about 18 months, he went away.

I've experienced the other sort of haunting, too. The one where you actually keep seeing - in the street, in shops, getting on and off buses, disappearing into the Underground - a person who cannot possibly be there. The lovesickness haunting. You've wept, agreed this is a far far better thing for both of you, embraced one final time, put the Seven Seas between you, then suddenly there she is! - half her age, twice her age, looking well, looking ill, carefree, careworn, alone, with someone else, forgetting you, not ever forgetting you. Once, in another life, I sat for half a day on a bench outside Biba in Kensington, convinced I had seen her go in and that so long as I waited without blinking I was bound to catch her when she came out. And I did. But it was not her. Not even like her. Except for the earrings.

I followed the spikes of her shoes the length of Charing Cross Road. The sway of her dress from the British Museum to the Victoria and Albert. The ribbons in her hair - for women wore ribbons then and I was an unashamed devotee of them - up and down every escalator in Oxford Street. All her components, but never her.

Concussion again? I suppose so. Bruise the heart and you see stars. Only with this sort of haunting you don't have the consolation of company: the little white dots that dance before your eyes don't arrange themselves into the shape you hope to see, and worse, they never talk to you. If you have the choice, choose your dad to ghost you.

I thought I knew all there was to know about hauntings, anyway, when suddenly I find myself prey to a new sort. Dreams, intimations, coincidences, all emanating not from fathers or lovers but from friends - old friends, very old friends. Not a night goes by now in which a friend from secondary or even primary school doesn't visit me, on some errand or another, in my sleep.

I cannot leave the house without a person I have never met before telling me he is the friend of one of my friends, or that he has just encountered or heard from someone I haven't encountered or heard from for over 30 years. At a party this week a stranger spoke to me of his love and admiration for X. I was filled with jealousy. I loved X. More to the point, the stranger had dined with X in New York only the week before, whereas I hadn't seen X since1964 when we'd fallen out in the Gaumont Cinema in Manchester because X reckoned the noise of my breathing was stopping him from concentrating on the film.

"I go to the pictures with women twice a week," I told him, "and none of them has ever complained about my breathing."

"I'm not a woman," he said, and that was that.

There it is in a nutshell. He wasn't a woman. Therefore he was dispensable. For one snuffle in a woman's ear you see off every boy you ever shared Plasticene or played poker with. You don't even turn around to wave.

Thirty-five years on, when you don't have a snuffle left in you, a perfect stranger comes up, asks if you remember X and tells you he loves him - your best friend! Then later that same night Y, not thought about for decades, appears in a dream to stop you killing ants on a stone wall in Torremolinos, where you hitched together in 1961. And the night following, K wrestles himself free of your solicitings, saying he wishes he could forgive you but he can't now and never will. What damage did you wreak on K? Ah, don't ask. But it had more to do with women than with ants, you can bet on that.

What do they want with me? Or rather - for ghosts come only when invited - what do I want with them? I have a horrible feeling I want their congratulations. Not for anything I've done exactly, more for having lasted, for continuing to be. "By God, you're still here, Jaco!" That would suffice. If only by lending a bit of credence to those early years, which grow remoter by the hour, as though not mine at all, but the property of someone else.