FORTY YEARS in the writing. It could take as long to read Clive James's book. What an amusing and irritating 40 years it would be, rewarding and eyebrowknitting in equal measures. In essence, the book is 100 essays on a parade of heroes, betes noires and supervillains . . . poets, essayists and historians, the occasional jazz musician or film director. The lack of a formal theme is made known in the introduction and foregrounded in the bland alphabetical ordering. Unity becomes apparent only after he has set off on a safari of sorts, which swiftly brings James into shooting range of his concerns, chiefly, the erosion of a global memory.

One area in particular, Vienna's pre-war cafe society, James attempts to hero-worship back into existence. Certainly the men he chooses to applaud, and juicily quote, leave an impression of a caffeinated Eden of unrepeatable intellectual giddiness. One man alone, the Viennese journalist Alfred Polgar, illustrates the point.

His one-sentence review of Pygmalion would have made Shaw chew his beard in envy: "A comedy about a man who turns a girl into a lady, but in doing so overlooks the woman."

The sinew resides in these chapters, where James wrestles from obscurity mittel-European thinkers, many of whom are unavailable in English and who James learned through the antwork of word-by-word translation.

But his mission is not merely to praise. He comes to warn us about Hitler. And Stalin. And Mao. "Ours was an age of extermination, an epoch of the abattoir." Why were intellectuals not only incapable of preventing last century's slaughter? Why in some cases did they assist it?

You would have thought the aforementioned tyrants were amnesia-proof, but still James worries. This author can still sniff the smarmy stink of the intellectual sophistry that greased Hitler's and Stalin's way to power.

"The problem of amoral intelligence, " he calls it. Those who gave no succour to the totalitarians are admired to the limit of James's affection and beyond restraint: "If there can be such a thing as a perfect person beyond Jesus Christ and his immediate family, Sophie Scholl was it." Those who kept quiet, such as Jorge Luis Borges in his South American context, are dismissed as moral pygmies.

Equally, academics Joachim Fest and AJP Taylor, who suggested the Nazis were a foregone conclusion, are left wiping metaphorical spit from their eyes. "Hindsight is not a view of the world, it is an indulgence of the self. It puts us in control of history, whereas the first thing we should realise about history is that we are not in control of it."

James scintillates on lesserknown writers (and his entry on Georg Christoph Lichtenberg is a masterclass on writing and evaluating prose) but stumbles on matters of popular culture, somewhat ironically given his selfproclaimed label of "premature post-modernist". He doesn't, however, concede one inch to that school's notorious relativism . . .

"Liberal democracy was, and is, reality" . . . and he's really only "postmodern" in his enthusiasm for snowballing high and low cultures to an amusing effect, presumably his reason for giving over Arthur Schnitzler's chapter to a humorous flaying of Where Eagles Dare's "intellectual squalor". Another chapter on Michael Mann doesn't get to grips with Mann's cinema at all, being only an extended riff on his film Heat. The piece has the whiff of a review that has sat unused since 1996.

A sheer cliff-face of learning, Cultural Amnesia is a difficult book to disagree with in its defence of liberal democracy. Is it traitorous to those ideals to suspect that it derives a goodly portion of its energy by swinging at straw men?

Fascism lingers, and there are commonalities linking the jackbooted pinheads of the 1930s and the jihadists of our new century. But some may have more faith than James in the memory of the public and its instinctive aversion to extremism.

With the author unable to restrain his cartwheeling erudition, the book's cornucopian bulk must in practice mitigate its value for readers who'd learn most from its forgotten masters. Rather than acting as a bulwark against cultural senescence, one comes to believe that what Clive James is most keen for you not to forget is Clive James.