It was Gustave Flaubert who said "I have no biography".

The remark, as his erudite and ever-faithful parrot, Julian Barnes, notes, was made in response to an enquiry by a journalist about his life. Art, for the author of Madame Bovary, was everything, the person who created it irrelevant. Of course, Flaubert may simply have wanted to avoid answering an awkward question. Who knows? On the face of it, though, it is the opposite of the view taken by the art historian Ernst Gombrich, who believed, "There is no such thing as art. There are only artists."

Barnes, one suspects, would like in his heart to side with Flaubert but knows that it is daft. Save for those anonymous neanderthals who decorated the walls of their caves with pictures of bison, the identity of artists informs and influences the way we look at their work. On a base level, it determines what we may be prepared to pay for it. Who among us would cough up $180 million for Women Of Algiers if it was signed "Pedro" rather than "Pablo" Picasso? In the art market, proof of authorship is all, irrespective of the quality of the painting. An ersatz Picasso may be better than a real one but that would never be reflected in its price at auction.

Of the 17 essays in this always entertaining and enlightening collection, none is devoted to the Spanish tyro. Nevertheless Picasso, like Flaubert, is never all that far from Barnes's thoughts. Considering Lucian Freud, who was as fecund a painter as he was a lover, Barnes remarks that Picasso was one of several painters Freud did not admire. Raphael was another, as was Leonardo da Vinci. He was particularly vituperative about Dante Gabriel Rossetti whom he dubbed "not just the worst of the Pre-Raphaelites but the nearest painting can get to bad breath". Freud's preference was for Titian, Rembrandt, Velázquez, Ingres, Matisse and Gwen John.

For good reason - given his treatment of women, his anti-semitism and his general rudeness - Freud discouraged biographers, threatening one with heavies when, Barnes recounts, he "started delving". However his death in 2011 released the floodgates and people who would never have written about him while he was alive, for fear of being duffed up or banished from his court, rushed into print. "He did whatever he liked," writes Barnes, "whenever he liked, and expected others to go along with it. His driving made Mr Toad look like a nervous learner. He would assault people without warning or, often, excuse. As a refugee child, he used to hit his English schoolfellows because he didn't understand their language; as an octogenarian, he was still getting into fist-fights in supermarkets."

What all this has to do with the application of paint on canvas is not entirely clear. Here, as elsewhere, Barnes appears happier to review the man instead of the work, though when he does apply himself to the latter he is perceptive and sensitive and unintimidated by reputation. Many of the artists considered - Delacroix, Courbet, Manet, Degas, Bonnard, Braque, Vuillard, etc - are French, which is no surprise given the author's incurable Francophilia, and were written initially for publications like Modern Painters, the Times Literary Supplement and the London Review Of Books.

All of them include a welcome personal element. In his introduction Barnes reveals how he grew to love and understand art. He is not himself a painter. Rather, like other notable writers, such as John Updike, William Boyd and Anita Brookner, he taught himself largely by looking and reading to appreciate art and contextualise it. As ever, Flaubert was his guide though he has no qualms about disregarding his advice. For while Flaubert believed that it was impossible to explain one art form in terms of another, Barnes insists: "We remain incorrigibly verbal creatures who love to explain things, to form opinions, to argue."

Here he is contentious without straying into vituperation. Regarding Pop Art, he writes: "It is about hanging around art, trying on its clothes, telling us not to be over-impressed by it. Warhol, for instance, is an artist rather as Fergie is a Royal." Which, it seems to me, is rather a witty way of saying Warhol is a phoney. Barnes is rightly suspicious of 'ideas' painters, because "any less-than-brilliant idea on canvas looks more exposed than does a less-than-brilliant 'aesthetic' sketch." Redon, whom he admires, "never drew the human body as well as he drew a tree". Courbet, meanwhile, was "a pioneer in self-marketing", selling photographs of his pictures to help spread their fame and planning "the first permanent exhibition centre devoted to a single artist - himself".

The last-mentioned is a reminder that Damien Hirst, Tracey Emin and others of their over-hyped ilk are inheritors of a tradition with deep roots. But whether what they produce may be called 'art' is a moot point. As Barnes acknowledges, most art is bad art, as most novels are bad novels. Worst of all, though, is bad personal art. "Much currently fashionable art bothers only the eye and briefly the brain, but it fails to engage the mind and the heart." That is surely the case. Even great artists have their off days, even Leonardo, even Manet, even Picasso, who said that if he was given a museum he would fill it.

What was once deemed shocking is now regarded as passé and what was once received with rapture is never allowed out in public. "The only thing that matters in art is what cannot be explained," Braque wrote. Remember that when next you read the gobbledegook accompanying a piece of conceptual claptrap.