I grew up with George Orwell. I was born in 1939, and Animal Farm was published in 1945. Thus, I was able to read it at the age of nine. It was lying around the house, and I mistook it for a book about talking animals, sort of like Wind in the Willows. I knew nothing about the kind of politics in the book - the child's version of politics then, just after the war, consisted of the simple notion that Hitler was bad but dead.

So I gobbled up the adventures of Napoleon and Snowball, the smart, greedy, upwardly mobile pigs, and Squealer the spin-doctor, and Boxer the noble but thick-witted horse, and the easily led, slogan-chanting sheep, without making any connection with historical events.

To say that I was horrified by this book is an understatement. The fate of the farm animals was so grim, the pigs so mean and mendacious and treacherous, the sheep so stupid. Children have a keen sense of injustice, and this was the thing that upset me the most: the pigs were so unjust. I cried my eyes out when Boxer the horse had an accident and was carted off to be made into dog food, instead of being given the quiet corner of the pasture he'd been promised.

The whole experience was deeply disturbing to me, but I am forever grateful to Orwell for alerting me early to the danger flags I've tried to watch out for since. In the world of Animal Farm, most speechifying and public palaver is bullshit and instigated lying, and though many characters are good-hearted and mean well, they can be frightened into closing their eyes to what's really going on.

The pigs browbeat the others with ideology, then twist that ideology to suit their own purposes: their language games were evident to me even at that age. As Orwell taught, it isn't the labels - Christianity, Socialism, Islam, Democracy, Two Legs Bad, Four Legs Good, the works - that are definitive, but the acts done in their name.

I could see, too, how easily those who have toppled an oppressive power take on its trappings and habits. Jean-Jacques Rousseau was right to warn us that democracy is the hardest form of government to maintain; Orwell knew that to the marrow of his bones, because he had seen it in action.

How quickly the precept "All Animals Are Equal" is changed into "All Animals Are Equal, but Some Are More Equal Than Others". What oily concern the pigs show for the welfare of the other animals, a concern that disguises their contempt for those they are manipulating.

With what alacrity do they put on the once-despised uniforms of the tyrannous humans they have overthrown, and learn to use their whips. How self-righteously they justify their actions, helped by the verbal web-spinning of Squealer, their nimble-tongued press agent, until all power is in their trotters, pretence is no longer necessary, and they rule by naked force.

A revolution often means only that: a revolving, a turn of the wheel of fortune, by which those who were at the bottom mount to the top, and assume the choice positions, crushing the former power-holders beneath them. We should beware of all those who plaster the landscape with large portraits of themselves, like the evil pig, Napoleon.

Animal Farm is one of the most spectacular Emperor-Has-No-Clothes books of the 20th century, and it got George Orwell into trouble. People who run counter to the current popular wisdom, who point out the uncomfortably obvious, are likely to be strenuously baa-ed at by herds of angry sheep. I didn't have all that figured out at the age of nine, of course - not in any conscious way. But we learn the patterns of stories before we learn their meanings, and Animal Farm has a very clear pattern.

Then along came Nineteen Eighty-Four, which was published in 1949. Thus, I read it in paperback a couple of years later, when I was in high school. Then I read it again, and again: it was right up there among my favourite books, along with Wuthering Heights.

At the same time, I absorbed its two companions, Arthur Koestler's Darkness At Noon and Aldous Huxley's Brave New World. I was keen on all three of them, but I understood Darkness At Noon to be a tragedy about events that had already happened, and Brave New World to be a satirical comedy, with events that were unlikely to unfold in exactly that way. (Orgy-Porgy, indeed.)

Nineteen Eighty-Four struck me as more realistic, probably because Winston Smith was more like me - a skinny person who got tired a lot and was subjected to physical education under chilly conditions (this was a feature of my school) - and who was silently at odds with the ideas and the manner of life proposed for him. (This may be one of the reasons Nineteen-Eighty-Four is best read when you are an adolescent: most adolescents feel like that.)

I sympathised particularly with Winston's desire to write his forbidden thoughts down in a deliciously tempting, secret blank book: I had not yet started to write, but I could see the attractions of it. I could also see the dangers, because it's this scribbling of his - along with illicit sex, another item with considerable allure for a teenager of the 50s - that gets Winston into such a mess.

Animal Farm charts the progress of an idealistic movement of liberation towards a totalitarian dictatorship headed by a despotic tyrant; Nineteen Eighty-Four describes what it's like to live entirely within such a system. Its hero, Winston, has only fragmentary memories of what life was like before the present dreadful regime set in: he's an orphan, a child of the collectivity. His father died in the war that has ushered in the repression, and his mother has disappeared, leaving him with only the reproachful glance she gave him as he betrayed her over a chocolate bar - a small betrayal that acts both as the key to Winston's character and as a precursor to the many other betrayals in the book.

The government of Airstrip One, Winston's "country", is brutal. The constant surveillance, the impossibility of speaking frankly to anyone, the looming, ominous figure of Big Brother, the regime's need for enemies and wars - fictitious though both may be - which are used to terrify the people and unite them in hatred, the mind-numbing slogans, the distortions of language, the destruction of what has really happened by stuffing any record of it down the Memory Hole - these made a deep impression on me. Let me re-state that: they frightened the stuffing out of me. Orwell was writing a satire about Stalin's Soviet Union, a place about which I knew very little at the age of 14, but he did it so well that I could imagine such things happening anywhere.

There is no love interest in Animal Farm, but there is in Nineteen Eighty-Four. Winston finds a soulmate in Julia; outwardly a devoted Party fanatic, secretly a girl who enjoys sex and makeup and other spots of decadence. But the two lovers are discovered, and Winston is tortured for thought-crime - inner disloyalty to the regime.

He feels that if he can only remain faithful in his heart to Julia, his soul will be saved - a romantic concept, though one we are likely to endorse. But like all absolutist governments and religions, the Party demands that every personal loyalty be sacrificed to it, and replaced with an absolute loyalty to Big Brother.

Confronted with his worst fear in the dreaded Room 101, where a nasty device involving a cage-full of starving rats can be fitted to the eyes, Winston breaks: "Don't do it to me," he pleads, "do it to Julia." (This sentence has become shorthand in our household for the avoidance of onerous duties. Poor Julia - how hard we would make her life if she actually existed. She'd have to be on a lot of panel discussions, for instance.)

After his betrayal of Julia, Winston becomes a handful of malleable goo. He truly believes that two and two make five, and that he loves Big Brother. Our last glimpse of him is sitting drink-sodden at an outdoor cafe, knowing he's a dead man walking and having learned that Julia has betrayed him, too, while he listens to a popular refrain: "Under the spreading chestnut tree/ I sold you and you sold me ..."

Orwell has been accused of bitterness and pessimism - of leaving us with a vision of the future in which the individual has no chance, and where the brutal, totalitarian boot of the all-controlling Party will grind into the human face, for ever.

But this view of Orwell is contradicted by the last chapter in the book, an essay on Newspeak - the doublethink language concocted by the regime. By expurgating all words that might be troublesome - "bad" is no longer permitted, but becomes "double-plus-ungood" - and by making other words mean the opposite of what they used to mean - the place where people get tortured is the Ministry of Love, the building where the past is destroyed is the Ministry of Information - the rulers of Airstrip One wish to make it literally impossible for people to think straight.

However, the essay on Newspeak is written in standard English, in the third person, and in the past tense, which can only mean that the regime has fallen, and that language and individuality have survived. For whoever has written the essay on Newspeak, the world of Nineteen Eighty-Four is over. Thus, it's my view that Orwell had much more faith in the resilience of the human spirit than he's usually been given credit for.

Orwell became a direct model for me much later in my life - in the real 1984, the year in which I began writing a somewhat different dystopia, The Handmaid's Tale. By that time I was 44, and I had learned enough about real despotisms - through the reading of history, travel, and my membership of Amnesty International - so that I didn't need to rely on Orwell alone.

The majority of dystopias - Orwell's included - have been written by men, and the point of view has been male. When women have appeared in them, they have been either sexless automatons or rebels who have defied the sex rules of the regime. They have acted as the temptresses of the male protagonists, however welcome this temptation may be to the men themselves.

Thus Julia; thus the cami-knicker-wearing, orgy-porgy seducer of the Savage in Brave New World; thus the subversive femme fatale of Yevgeny Zamyatin's 1924 seminal classic, We. I wanted to try a dystopia from the female point of view - the world according to Julia, as it were. However, this does not make The Handmaid's Tale a "feminist dystopia", except insofar as giving a woman a voice and an inner life will always be considered "feminist" by those who think women ought not to have these things.

The 20th century could be seen as a race between two versions of man-made hell - the jackbooted state totalitarianism of Orwell's Nineteen Eight-Four, and the hedonistic ersatz paradise of Brave New World, where absolutely everything is a consumer good and human beings are engineered to be happy. With the fall of the Berlin Wall in 1989, it seemed for a time that Brave New World had won - from henceforth, state control would be minimal, and all we would have to do was go shopping and smile a lot, and wallow in pleasures, popping a pill or two when depression set in.

But with 9/11, all that changed. Now it appears we face the prospect of two contradictory dystopias at once - open markets, closed minds - because state surveillance is back again with a vengeance. The torturer's dreaded Room 101 has been with us for millennia. The dungeons of Rome, the Inquisition, the Star Chamber, the Bastille, the proceedings of General Pinochet and of the junta in Argentina - all have depended on secrecy and on the abuse of power. Lots of countries have had their versions of it - their ways of silencing troublesome dissent.

Democracies have traditionally defined themselves by, among other things - openness and the rule of law. But now it seems that we in the west are tacitly legitimising the methods of the darker human past, upgraded technologically and sanctified to our own uses, of course. For the sake of freedom, freedom must be renounced. To move us towards the improved world - the utopia we're promised - dystopia must first hold sway.

It's a concept worthy of doublethink. It's also, in its ordering of events, strangely Marxist. First the dictatorship of the proletariat, in which lots of heads must roll; then the pie-in-the-sky classless society, which oddly enough never materialises. Instead, we just get pigs with whips.

I often ask myself: what would George Orwell have to say about it?

Quite a lot.

· This is an edited extract from Margaret Atwood's contribution to BBC Radio 3's Twenty Minutes: The Orwell Essays series, broadcast tonight at 8.05pm. Roy Hattersley's and John Carey's essays will be broadcast at the same time on Tuesday and Wednesday respectively. Margaret Atwood's latest novel, Oryx and Crake, is published by Bloomsbury.