Everything to do with Brecht comes freighted with a cargo of puzzle and paradox So it is with these outraged cries of "Thief!". Brecht's practice did keep faith with his theory in one respect at least. He always urged that the creative to-and-fro of collaboration should shape and change his work as the realities around it mutated. Hence the finest items that bear the "Brecht" trademark always reflect a long process of testing and tweaking in which many hands and many minds may claim a share. And his theoretical ideas also include the theoretical idea of their own planned obsolescence The Life of Galileo itself went though three major phases. The play began with the eve-of-apocalypse original written in haste in his Danish exile in 1938, before evolving through the Hiroshima-era version that Brecht worked on in Los Angeles with his good friend Charles Laughton - while "your people and mine were tearing each other to pieces", as a poem says. When the atomic bomb exploded from theory into practice in 1945, Brecht wrote that "Overnight the biography of the founder of the new system of physics read differently".

Then, in the state-sanctioned sarcophagus of the Berliner Ensemble, came the final Berlin text of 1953, which in fact sharpens the play's anguished sense of complicity in an unjust social order. Brecht, like Galileo's Earth, still moves in spite of what the powers-that-be decree. Mocking the efforts by his family to hold this ever-fluid stream of work inside a legal coffin of copyright, his best interpreters remake and reshape it every year. Listen (for instance) to Nina Simone singing Pirate Jenny's song from The Threepeny Opera. Simone finesses the lyrics to turn Jenny into a black maid at a Deep South hotel packed with the racist good ol'boys on whom she plans a spine-chilling revenge.

It's a stunning performance, more truly Brechtian than any textbook rendition meant to pacify the purists. In one of the eye-opening conversations recorded by the critic Walter Benjamin during his mid-1930s visits to the Danish island where Brecht hid from the Third Reich, Brecht offers as an artists' maxim: "Don't start from the good old things, but from the bad new ones". The same always goes for understanding - and performing - Brecht himself. " Truth is born of the times," says Galileo prior to his surrender, " not of authority." These tenets still fail to appease those critics for whom Brecht's impenitent public Stalinism (whatever his gnawing private doubts) sticks forever in the craw.

Yet in backing a brutal ideology whose benighted simplicities contradict the light and life of his own strongest work, the writer shared a self-betrayal with many of his greatest literary peers. Think of TS Eliot damning the modern urban culture that harbours "any large number of free-thinking Jews"; of Ezra Pound broadcasting in favour of Mussolini's Fascism... or (to descend from tragedy into farce) of the ageing, deluded WB Yeats who cheered on General O'Duffy's pantomime "Blueshirts" in Ireland. The most revealing comparison of all, I think, comes not from the crowd of Modernist giants who flirted with far-right barbarism but from one of Brecht's earliest inspirations: Rudyard Kipling The young, anarchic Brecht loved Kipling. You can feel the rollicking plebeian rhythms of the latter's verse in his poetry from the 1920s onwards. Kiplingesque parody and tribute unite in a ballad such as the "Cannon Song" from The Threepenny Opera, with its gung-ho squaddies: "When they come face to face/ With a different breed of fellow/ Whose skin is black or yellow/ They quick as winking chop him into beefsteak tartare".

At a deeper level, both of these provoking arrivistes take a brash and bold artisan's approach to literature. They make the writer's study into a humming workshop where impromptu tools do unusual jobs. Both temper political stridency with a lyrical sympathy for undervalued crafts and trades and, above all, for the enduring wonder of the natural world. From his Danish hideaway Brecht wrote that "Inside me contend/ Delight at the apple-tree in blossom/ And horror at the house-painter's [ie Hitler's] speeches./ But only the second/ Drives me to my desk" Thankfully, that was never wholly true. Crucially, both busy innovators fashioned free-spirited work that still liberates other writers while endorsing a system of high-minded plunder and despotism that brought only hardship and hopelessness to millions: Soviet Communism in Brecht's case, British imperialism in Kipling's. Both figureheads believe on the podium yet doubt at their desk. If you wished to draw a distinction, you might argue that Kipling tended to ratify the imperialists' pack of lies more sincerely than did Brecht with the Stalinists' equivalent.