IN the wake of the former CIA analyst Edward Snowden's revelations about state surveillance, I thought I'd reread George Orwell's 1984, written nearly 70 years ago on the island of Jura.

I was taken aback by how prophetic it is. When I first read this novel at school, before personal computers and the internet, the idea of two-way interactive "telescreens" in every home and workplace seemed like improbable science fiction. Not today. Orwell, through an extraordinary feat of imagination, had described the internet nearly half a century before it was invented.

But he could never have imagined the sheer power digital technology would place in the hands of the state to record, store, search and collate information. In the Ministry of Truth they had voice recognition software - the "speakwrite" - but ultimately information was still retained on paper. Imagine Big Brother having access to Big Data, and acquiring the ability to hold and search petabytes of information, in the way GCHQ and the American National Security Agency apparently do. Or to monitor, record and search millions of telephone conversations like Verizon.

Winston Smith could still go off line, at least for short periods. But today, BB would know exactly where he was thanks to ubiquitous CCTV cameras and global positioning software on mobile phones. Then there is all that Orwellian-sounding "metadata" that can be and is mined from the net, allowing access to our very unconscious minds through algorithms that analyse what we watch, buy and read; whom we meet and where we go. As for Facebook: Orwell would never have believed it. Millions of people putting their private thoughts onto a public record that can never be erased.

But Orwell got the basics right. As Winston Smith's banned book explained, what differentiated 1984 from all previous repressive regimes was that "in the past no government had the power to keep its citizens under constant surveillance". Freedom has, since the dawn of civilisation, rested on our right to live our lives free from arbitrary interference and monitoring by the state. Orwell's message was that without democratic control and rigorous accountability, without a presumption of privacy and freedom of thought, the coming technology of surveillance had the capacity to extinguish most of what it means to be human.

How little we have learned. If anyone had suggested in 1948, when Orwell was writing, that the police or security services should be allowed to copy and record all letters and telephone conversations, and keep these records indefinitely for future reference, there would have been a public outcry. Privacy was regarded as an inalienable right. The idea that a police force, however benevolent, could be allowed indiscriminately to monitor where we go, who we speak to and ransack our private diaries and notes, would have outraged a country that had just fought a war against fascism.

And it wouldn't only have been liberal newspaper editors who would have been sounding the alarm. 1984 wasn't a piece of left-wing propaganda. The hero's namesake, Winston Churchill, opposed identity cards and mass surveillance after the Second World War precisely because they were the hallmarks of totalitarianism. Conservatives then would have been appalled at the idea of a secret policeman at the end of every telephone wire, in every post office, at the end of every street potentially monitoring everything we do.

And if the head of M15 in 1948 had suggested, as director-general Andrew Parker did this week, that such an apparatus of surveillance was necessary to combat communist terrorism, there would have been questions in the Commons and demands for him to resign. Justifying mass surveillance on the grounds of fighting terrorism is straight out of 1984 and the apologia of the Thought Police: "If you aren't doing anything wrong, you have nothing to fear."

Yet here we are today, calmly accepting the constructing this industry of intrusion. We're told we don't need to know about it because it is all for our protection. That if the secret services aren't given the power to record and monitor everything we do, terrorists will be free to wreak havoc, kill and destroy. A policeman needs to sit in our living rooms so that we can sleep safely in our beds at night.

Mr Parker claims that the Guardian's recent revelations about the extent of secret and, in America at least, illegal surveillance of the internet is itself of benefit to terrorism. "It causes enormous damage," he said, "to make public the reach and limits of GCHQ techniques. Such information hands the advantage to the terrorists." Just examine that proposition. He claims that our knowing about programmes like Prism and Tempora that can access and store our activities on the internet will itself help the terrorist. I profoundly disagree. The terrorists already know they are under surveillance and act accordingly. It is the rest of us who have been kept in the dark about the behaviour of a state that is supposed to serve us, not spy on us. He might as well have said: Ignorance is Strength, the mission statement of the Ministry of Truth.

Of course, the police and security services must have secrets and they have to monitor those suspected of terrorism or any other serious crime. No-one is suggesting anything other than this. But it should be within the rule of law and founded on the presumption of innocence. No system of justice should allow the police, armed with search engines, to go on fishing expeditions through our private communications looking for things that might incriminate. That is the very definition of a police state.

We know where this ends up. It is journalists held for nine hours at airports, having to give up their passwords and encryption keys, not because they are suspected of breaking any law but because they may possess information "of interest to terrorists" - an entirely subjective charge. It justifies a degree of intrusion into our personal affairs that is not compatible with a free society. Perhaps we have given up on the idea of freedom, as an anachronistic, analogue hangover from the days when people still read books.

The Snowden revelations have aroused furious controversy in America and continental Europe but, here in Britain, land of Orwell, there has been very little public concern. It hasn't even been debated in Parliament. This complacency about the see-through society is troubling. We seem to have forgotten how information can be used and abused by tyrants, big business, big government. Can no-one imagine how this might be used by governments in the future?

As I write, the Privy Council - an unelected remnant of feudalism - is deciding the limits of press freedom and may be about to put the print media under a form of statutory regulation for the first time in 300 years. Perhaps the lack of proper teaching about history in schools has allowed us to forget the abiding lesson of history: that power corrupts. Orwell realised that knowledge is power; and absolute knowledge is absolute power.