Sigmund Freud was like a Pharaoh. He built his monuments during his life - imposing writings, a byzantine legacy of professional institutions to continue his work and preserve his contribution to science, as he fondly believed it to be. Surrounded by books and Greek, Roman and Egyptian statues in his old house in London, a mausoleum kindly preserved by his daughter Anna just as he left it, I nervously eyed the couch on the other side of the room. Perhaps perceiving my nervousness, Freud could not resist a sly dig at my frosty refusal of a fat cigar, by instructing me that smoking is one of the greatest and cheapest enjoyments in a life that is principally filled with frustrations and hardship. We began to talk.

Fifty-six years ago, you moved from Vienna to Hampstead, where, since your death, has gathered a ghetto of patients, daily visiting their analysts, faithfully following in your footsteps. Does this please you?

As the poet says, Ins jenseits kann man nichts mitnehmen - you can't take it with you. Nothing of this belongs to me, neither the house nor the psychoanalytic movement. Let each have his totem; the alternatives are varieties of sex and drugs and rock 'n' roll, as you say these days - palliatives that are not to be disdained, I might add.

But aren't you horrified by the explosion of bizarre therapies associated with your name, particularly in America?

I started out my working life employing hypnotism and, having for years been a zealot of that mysterious craft, I have never underestimated the power of suggestion. Psychoanalysis was an attempt by a rationalist to harness the fundamental power, the erotic, without abusing the liberty of the patient. There was never any guarantee that it would always, or often, achieve that goal. The postmodern therapeutic imperative at least shows that the idea had legs in it. As for abandoning it, healers could not relinquish therapy even if they wanted to, because the patients have not the slightest intention of doing without it.

But no one is taken in any longer by your claim that psychoanalysis is the only respectable, the only scientific version of therapy.

I am always condemned for the sake of some higher ideal. While I was alive, it was the purity of the women, children and the family - remember, my books were treated as pornography by booksellers in London in the Twenties. Now, in the Nineties, I'm not only a purveyor of shoddy goods well past their sell-by date, but a latter-day astrologer, a charlatan, a liar and a cheat to boot. Whatever will be next?

Let me ask you this. Do you really want to behave towards truth as if she were your wife, so that the prospect of finding out that she is not as she seems is tantamount to her adultery? Modern-day apologists for science are, I have noted, particularly horrified at the possibility that truth might be faithless; they seek certainty at all costs, just as the jealous man needs to know everything, usually at his own expense. Psychoanalysis flaunts the infidelity of truth. The man who is too fearful to entrust himself to the uncertainties of life tries to make an honest woman of truth by imprisoning her in a laboratory. To him, it always seems like a scandal and a mystification to be told that you can only cure through love, and thus can only discover truth through love.

Yet judged by today's moral standards, you fare pretty poorly: you never noticed that your precious civilisation was imperial and colonial, and founded on racism, except when you talked condescendingly about the habits of primitives; you entirely overlooked the stratification of society by classes and the oppressive economic relations under which the working classes and their neuroses are generated; and your theories of femininity are notorious as the bulwark of the conservative forces that kept women tied to family, babies and the great god penis.

Forgive me for saying so, but you are speaking the cultish dialect of the Seventies, the new Trinity of Race, Class and Gender, by which I am condemned. It is true that I spoke of primitives and overlooked the force of race in human affairs: I was an educated Jew who believed in the universal ethical standards of Western culture. It is true that I do not side with the revolutionaries: for all the justice of the cause of the poor and propertyless, I see no solution in the egalitarian politics of envy.

It is true that I doubted the practicality of women's demands for equality. There I have to admit that perhaps I was wrong: penis envy shows itself to be more capable of sublimation than I thought - and I have to thank my disciple Woody Allen for reminding me that both men and women are wholesale sufferers from penis envy.

The thing that has really surprised me is your obsession with culture.

The Oedipus complex I discovered in Sophocles' play is now played out in that modern mixture that I could never have foreseen: the potent combination of art and bodily intoxicants that goes under the name of the mass media. I always had considerable respect for mankind's creative manipulation of the body through its chemistry - I did, don't forget, subject myself to the pleasures and hardships of cocaine, and not only in the interests of science. But it is clear that I underestimated, and am very impressed by, the consolations that can be had through becoming addicted to culture.

But I find myself perplexed by your criticisms. You talk of big issues - of race, sex and class - but your world is full of smaller and smaller groups, each with its issue, its unstable identity, its resentful demand to be treated as a special case. From the ugly resurgence of nationalism, with small nation pitted against its neighbour, via the bickering and open warfare of your religious sects, to the sexual politics of the pampered First World, I see nothing but what I once called the narcissism of minor differences.

To elevate a sexual predilection into a political principle is surprising - though far be it from me to be surprised by the importance you sometimes give to sexual pleasure.

You took the words out of my mouth. Because to be called a Freudian is for us to be obsessed with sex, to be continually finding sex in places where it doesn't belong. Would you reconsider your own obsession with the importance of sex?

Do you doubt that sexual satisfaction is one of the chief and finest things in life? Why turn on it as a false god, simply because it does not always make you happy and because Aids has blighted it with fear and provoked in you the desire to deprive others of its pleasures, just as syphilis did for my era? I never thought sex was a path to heaven nor that it would ever cease to be in conflict with other principles that human beings hold equally dear. However, I must be careful; after all, I am in the country that still clings to the principle 'no Freud please, we're British'. If you are reluctant to admit that sexual desire is to be found at the very heart of your lives, please, at the very least, recognise that we - and particularly you British - are still all sexual hypocrites.

But it is not only sex that gives you a bad name. In recent years anti-Freudians have accused you of covering up the sexual abuse of children and alleged you fabricated evidence to prove your theories; then we have neo-Freudians demonstrating that therapists are implanting false memories in their patients' minds. It doesn't look good, you must admit.

When therapists protest against the sexual abuse of children, it is like surgeons in casualty militating against the invention of the motor car; to be sure, it is the cause of the injuries they have to heal, but their job is to heal not to reinvent our transportation systems. I never confounded psychoanalysis with a moral crusade; quite the opposite. Nor should my critics.

As far as false memories are concerned, I would like to claim some priority in their discovery: I called them fantasy, daydream and screen memories.

The harshest criticisms of you at present are: Freud is all fine words, but in the end he's a liar and a cheat. How do you reply to this verdict?

We each have our neurotic compulsions. Mine was to tell a little, not too much, of the truth about myself. The call to tell the truth is a pathology peculiar to this century. As my fellow-countryman and pessimist, Milan Kundera, writes: 'The whole moral structure of your time rests on the Eleventh Commandment: Tell the truth]' And you are the prophet of the Eleventh Commandment, sufficiently powerful to drag me back from immortality to demand an answer to your impertinent questions.

John Forrester is a lecturer at King's College, Cambridge. He has written extensively on Freud.