Whether David Davis makes of himself a public hero or a popular buffoon by his plunge into notoriety, he stands for me as an allegorical monitor of our times. His behaviour has been quixotic, but like the great mad progenitor of the condition, Don Quixote of La Mancha, he is fighting a cause in a truly fateful battle - a battle for liberty of the human spirit.

It is not just a matter of those 42 days, of habeas corpus or even of human rights in the political sense of the phrase: it is an elemental struggle that is dividing the British again into two nations, as Benjamin Disraeli saw them long ago. They are in vulnerable condition anyway, their natural resistance weakened - all in a mess, demoralised, lacking confidence and conviction, enervated by failure and alien principles, swept this way and that by the forces of a rotten materialist culture.

And of the contemporary two nations, it seems to me, by far the greater is giving up on liberty. Anyone can see that in Britain, 2008, individuality is being suppressed, so that year by year, generation by generation, the people are being bullied or brainwashed into docile conformity. What is more ominous is that so many want to be docile. They want to be supervised, cosseted, homogenised, obedient.

The ubiquitous CCTV cameras are the emblems of this malaise, not because of their existence but because people accept them as necessary for the public good: the police tell them so, councils tell them so, statistics proclaim it, and so they believe it, and are perfectly willing to be spied upon, night and day, wherever they go, by unknown, invisible strangers out of sight.

The so-called war on terror is of course the supposed excuse for this appalling violation of all our privacies, together with the ominous rise of the secret intelligence agencies. The public has been gulled into acceptance of the supervisory state, with all its paraphernalia of surveillance and identity cards, DNA databases, armed police and arbitrary search, by the mantra: "If you don't do anything wrong, why worry?"

Brainwashed by a tabloid press of brilliantly insidious techniques, then, numbed by the relentless mediocrity of television, half the people have willingly forfeited the right to make up their own minds, and mutely accept indoctrination. "He's not afraid of anything," I overheard one young mother say to another, watching her three-year-old clambering over an obstacle, but the reply came straight from the state: "Oh that's dangerous, you must never allow him to think like that."

Even the middle classes, once the very backbone of robust individualism, are not immune to the contagion. They all think twice about expressing their views in case they say something that is politically incorrect. They preposterously mollycoddle their children, not only because they have been so repeatedly warned of life's unspeakable dangers but also because they wonder what the neighbours will think. They are officially encouraged to snoop and sneak on their fellow citizens, so snoop and sneak they do.

And when you are afraid to say what you think, it is a step nearer to the most dreadful condition of all: being afraid of what to think. As I see it, Davis's display concerns not just political liberty but liberty of the mind, of the identity, of the spirit - even, patriots might sententiously say, of the national soul. It is not simply 800 years of hard-won political rights he is defending, it is nothing less than a view of life itself, which civilised peoples have so pain-stakingly fashioned down the centuries. It has been an old pride of the British that they, above all, have honoured the truest forms of freedom, with all its anomalies, eccentricities and humour, above and beside all politics, obeying only laws they respect.

A few more generations of nagging and surveillance and we shall have forgotten what true freedom is. Young people will have foregone the excitements of risk, academics will temper all thought with caution, and the great public will accept without demur all restrictions and requirements of the state. Ours will be a people moulded to docility, perfect fodder for ideologues. Then if the one nation of the British slides into autocracy, guided by opportunist or witless politicians and a gullible press, the other nation will be goaded towards despotism too. Already every free soul, I suspect, has sometimes wished that we had a benevolent dictator to sweep all the nonsense aside, the flabbiness and the conformity, the brainwash and all. Some day the structure may crack, and we shall find ourselves under the autocracy of conformists or libertarians - both forced into totalitarianism in defence of their own philosophies.

So perhaps Davis is a prophet as well as a politician. When he talks of habeas corpus he is echoing ideas far older and more profound, reaching back to the earliest yearnings of antiquity, the first glimmerings of human individuality, when our ancestors began to break from tribal disciplines and devise preferences of their own. Tribalism is what every despotism hopes to impose on its people. It is the will of the party, which Davis has apparently flouted. It is the will of the majority, which is one reason why Gordon Brown feels no need to put up a candidate at Haltemprice and Howden. Today the whistleblowers are our guardians of the spirit, and I like to think that Davis is one of them - a true successor of the grand old knight of Castile, but alas, tilting at windmills that are all too real.

· Jan Morris is a historian, travel writer and former Guardian correspondent

janmorris1@msn.com