Flourishing: Letters 1928-46 by Isaiah Berlin, ed. Henry Hardy

We meet a portly, dark, funny young man of 19 whose cleverness will clearly take him far. There are no serious setbacks, and yet the story is exciting. As we leave him, aged 37, many readers will surely sign up for more.

This first tranche of Isaiah Berlin's letters has two novel-like plots. They are, as the influential historian of ideas and master-networker of Oxford would have known, all the better for lurking in an unstated way. He writes like Henry James (and thinks a bit like William James). He's elliptical, intense, a sturdy mind drunk on the subtleties it sees, repelled and attracted by violent events.

The first storyline concerns Berlin wondering in his thirties if he can be bothered to be a serious philosopher. He decides not ("I didn't lie awake puzzling about philosophical problems"), and settles for the study of the intellectual history of the Enlightenment, and its working-out among Russian intellectuals in the 19th century.

The second is whether he is any sort of man of action. Finding out that he could be - dabbling in Zionist politics, and reporting on US politics to the Foreign Office from Washington during the Second World War - only proves to him that Oxford academic politics is more his scene (métier would have been his multi-lingual word), and just as taxing.

It's easy to see that such a man would have a wide range of correspondents and hardly surprising that he indulges them (and us) with long ("how I do run on"), important accounts of what he thinks about the world, philosophy, classical music, and modern poetry and novels. But that's not why these letters will be widely read. His flaws let us in: Berlin is a gossipy, camp snob. "Jews have no taste", he writes: "The English are C3". Americans are "2 + 2 = 4" sorts of people. Louis MacNeice remarks that the most suitable present for him would be a saucer of milk.

To reactionary eyes - mine - Berlin is too effortlessly Hampstead Liberal (he positively despises "the awful" F A Hayek), but it is almost a comfort that he has so large and obvious a deficiency as to appear to believe that a fastidious distaste for the totalitarian is all there is to liberalism. As he progresses from being what he calls a "priggish" and "elderly" schoolboy through to a senior Oxford figure, with distinguished cerebral war service under his belt, we are watching someone grow into his cleverness.

Insecurity, flashiness and bitchiness are increasingly swamped by something more satisfactorily wry, witty and sad, but not altogether unchildlike. Erudition and volubility clearly always made him a taxing acquaintance: an American newspaper editor met him, and said he hadn't understood a word Berlin said but would publish anything he wrote.

It is hard to know what were his sexual or emotional proclivities. When Berlin refers to a period when his "emotional life" was "wonderfully placid" in Washington in 1944, the explanation is tucked away inside two brackets and inverted commas: "{(my 'friend' left US 6 months ago)}". You have to turn to Michael Ignatieff's biography to find that this was Berlin's first serious love affair, and probably not a consummated one either.

Henry Hardy - Berlin's representative on earth and editor of all his works - gives us a wealth of material as well as footnotes, and sometimes mocks himself for overdoing it. His preface itself has a footnoted preface which discusses prefaces. Still, I needed more of this ancillary stuff than an educated person should.

Berlin seems not to have selected as intimates those who could be useful to him. The poet Stephen Spender or the philosopher Stuart Hampshire ("Hants") are among the several luminaries he wrote to often, some of them before they became famous. Other correspondents were interesting, not powerful. Many of these letters retell recent formal conversations or reports. We are given undressed accounts that wouldn't quite do for the grown-ups.

A staunch Zionist, Berlin does not write about his own Jewishness, but it is everywhere. He describes himself as a Mediterranean. He loved his proudly and busily Jewish parents, who fussed over their prodigious son. But his letters to them are those of a respectfully bossy superior. Aged 34, he counsels them that "we" need a seven-roomed house. Russia moves him more than anywhere, perhaps as the place from which he had been exiled. But we detect that home is his Jewishness and his family. He has a profound taste for routine and cosiness: "my love of the womb... (a womb with a view, a womb of one's own etc)": perhaps the most meant, and the only feeble, joke in the whole collection.

Richard North is media fellow of the Institute of Economic Affairs