I doubt I ever exchanged more than a couple of dozen words with Charles Kennedy.

Polite words, spoken affably, by a politician who was patently no one's fool, but just small talk. For me, never more than a visitor to Westminster, the late MP was a nodding acquaintance.

For all that, it was good to know he was around. Even his wit was reassuring. Mr Kennedy's death is a reminder that a formidable Scottish generation, ferociously intelligent people of all parties, is diminishing steadily. They will have successors - the still young, 32-year veteran knew all about that - but not replacements. A way of doing politics, Scottish politics, is fading.

That was one part of Mr Kennedy's value. The traditions of Scottish Liberalism have been too often honoured in the breach, but he did not resile from old commitments. That's partly comical, given that he was never actually a Liberal. It mattered more when Nick Clegg was engineering his coalition with David Cameron. Mr Kennedy let it be known, without song or dance, that this was a disaster in the making for a party of the radical centre.

His defeat in Ross, Skye and Lochaber was, you might think, proof enough. The seat (more or less) that the 23-year-old once took from the Tories passed to the SNP. Amid the rout, where did that leave the Scottish Liberal Democrats and the beliefs for which Mr Kennedy was an advocate? Whatever he thought in the aftermath, he must have thought often about contrasts.

In 2005, he led his party to 62 general election wins across the United Kingdom. A decade later, after the Coalition he opposed - and the tuition fees deceit he disowned - there are eight Liberal Democrat MPs. In Scotland, there is a single former Scottish Secretary more interested in his struggles with truth and reality than with anything as mundane as an argument over principles. In many of yesterday's tributes, the word "prescient" was granted to Mr Kennedy. It was apt.

He had his troubles. These come in all walks of life, but they allow politicians no escape. In Westminster (or Holyrood) there is no hiding place from round-the-clock news. Go home, to the constituency in which you were raised, in which everyone knows your face and a lot more besides, and even the offers of respite and affection are conditional. The rest of us can leave the job behind, now and then. Affable, clever and compassionate Charlie Kennedy was a prisoner of his career.

As are they all. Like Mr Kennedy, they choose the existence. Good, bad, or ordinarily inept, they pursue a life that is seductive, strange and dangerous. How bizarre is politics? It fell to Alastair Campbell, with scars in common, to find a way to describe the worth of his dead friend in a raw, aching blog early yesterday. Their political arguments were one thing. Tony Blair's former director of communications wrote that Mr Kennedy "spoke fluent human, because he had humanity in every vein and every cell".

That's a deal more, I think, than the usual piety. But Mr Campbell was also saying something, inadvertently, that ought to bother voters as much as it should trouble those who haunt Westminster or Holyrood. What do we do to those we elect if our greatest praise is to say they manage to remain human?

Those who knew him best attest that Mr Kennedy was ever smart, funny, "the best of company", and always able to overcome his shyness and speak "like an ordinary person". The praise, unexamined, is easily understood. Unlike so many, the late MP did not seem out of touch, or bereft of self-awareness, or incapable of seeing the funny side. But is this truly the most we hope for in public servants?

Contempt for politicians is general and relentless. The reasons, from unceasing arrogance to expenses claims, are well-established. Then you come across one who is liked by all, who has died too soon, who did his honest best for the place where he was raised, and the reactions are reflexive. Why can't they all be like that? When did "fluent human" become unusual in political life? Set aside the eternal crew of the greedy, the vain, the self-seeking, and - let's not kid ourselves - the mad. What has become of politics to make a Charles Kennedy a rarity?

Two answers are thrown in headlong collision. One is that anyone who fancies political life has to be a little screwed up to begin with. You could wonder about Mr Kennedy, the Glasgow graduate pursuing his Fulbright researches in Indiana, and if he ever thought about the other roads his life might have made possible. Westminster is an institution: supply (he sometimes did) your own jokes. He might have done many other good and useful things with his time, but spent his years in service to a political tradition on the fringes of power.

Then there's the other answer: we, the rest of us, might just get the politicians we deserve. They infuriate or disgust us until a Charles Kennedy comes along. Then, for a little while, we remember what politics should be or could be. But we, most of the time, with a stack of evidence, still don't trust them. In their turn, they fear and distrust us.

Voting systems and party games have very little to do with the ruined condition of this social contract. It has probably been in decline since the advent of universal suffrage, since (most of us) ceased to cast ballots as we were bid and accept whatever laws were handed down. The conclusion remains. Mr Kennedy is held in affection as an honest man who did his human best. This counts as odd, anomalous, unexpected. And that's also an odd fact.

He was being praised yesterday for his opposition to Mr Blair's Iraq fraud. Some of the facts have been bent a little out of a shape, but the essence remains. Mr Kennedy (and Menzies Campbell) held to the view that continued weapons inspections would have resolved America's pre-ordained argument with Saddam Hussein better than bombing. Others, never forget, said much the same thing. But a political consensus took us to war in the absence of facts and the presence of public opposition. So why was Mr Kennedy, in the language of the time, deemed "out of step"?

As euphemisms in politics go, "affable" never ceases to be useful. It can cover everything from bonhomie to the afflictions which bore down on Mr Kennedy, by all accounts, for a large part of a good life. Any number of tributes yesterday will have come from people whispering: "There but for the grace of God". But judging humanity by its woes would leave very few of us qualified to comment. We would be better wondering about the nature of a politician's life, and what it does to those whose first instinct is to speak "fluent human".

Mr Kennedy will be missed, even by those who didn't manage so much as a nod in some room where political types prowl. The better thing would be to think about why he will he missed.