Modernism: The Lure of Heresy, By Peter Gay

Make It New; Less Is More; Form Follows Function; Ornament Is Crime: it would almost be possible to do a history of Modernism entirely in slogans, since one of the most striking aspects of this long and disparate quasi-movement was the obsessive eloquence it spent on defining and promoting itself. From its beginnings in abreaction from 19th-century Romanticism to its death, real or faked, in the arena of post-structuralism, Modernism was a campaign of iconoclasm and inventiveness that was as vigorous in its invective against the anti-progressive as it was in its apologies for the individual talent. Having something to say was a criterion for entry, and the more shocking the better, whether it was Picabia's dictum that art should be "useless and impossible to justify", Picasso's statement that modern art was "a sum of destructions" or even Diaghilev's famous greeting to aspirant dancers: "Astonish me!". One critic early in the century perceptively labelled the mob of avant-gardists, drunk on this ferment of novelty, "the herd of independent minds".

As an Enlightenment historian, a biographer of Freud and the author of a sequence of books on the Victorian era and the rise of the middle class, Peter Gay has been laying the foundations of this book for a long time. This is not a comprehensive history of the movement – a project that might border on the insane – but it's broader than most. It takes in representatives from painting, sculpture, music, literature, architecture and cinema, but it eschews, for example, philosophy and physics.

Gay sees two salient traits in Modernism: the desire to offend tradition and the wish to explore subjective experience. Other features – anti-authoritarianism, abstraction in art, functionality in architecture – follow after, but "the one thing all modernists had indisputably in common was the conviction that the untried is markedly superior to the familiar, the rare to the ordinary, the experimental to the routine". He locates the beginnings of the movement with Baudelaire, whose calculatedly explicit verse and impulsion to show "mon coeur mis à nu" led to prosecution and outrage, as well as to an accolade from Flaubert, literary modernism's other founding father. "You resemble no one," Flaubert told him. In one of the striking comparisons that make this book notable, Gay points out that some years later we find Monet writing something very similar to Bazille: after decamping to the provinces to paint in solitude, he exclaims that "what I do here will at least have the merit of resembling nobody." A new criterion of value had been introduced.

Modernism is often portrayed as an elitist movement with an almost psychopathic hatred of the middle classes. According to Gay, "uncritical reliance on such testimony has distorted the history of Modernism almost beyond rescue." His book presents compelling instances not only of the part played by the middle classes in funding and patronising Modernist artists and architects, but also of their adaptability to the ideas proposed by the movement. Far from being épaté, the bourgeois created a market for modernist art, and some of the most vociferous of Modernism's firebrands ended up crossing the floor themselves. Even Marcel Duchamp, whose nihilistic conceptualism makes him Gay's candidate for the assassination of 20th-century art ("he was at the scene of the crime, heavily armed, for decades before later suspects like Andy Warhol were born"), ended up supervising the installation of his own work in the kind of museums he had once incited his comrades to burn.

Gay's prose is erudite and lucid, his range of example wide. Even its subsidiary thesis, that not only Modernism's currency but art's in general was devalued by the advent of Pop and Conceptualism in the 1960s is leavened by a final chapter in which Gay evinces a qualified hope for the future of this recumbent movement. Whether it lies with Frank Gehry and Gabriel García Márquez is open to debate; but so is a good deal else in this absorbing, occasionally maddening book.

Heinemann £20