Anyone who paints depictively, or likes to see their contemporaries do so, must feel besieged by intellectual doubts. Realism, naturalism, figurative painting -- whatever you call it -- is haunted by a sense of exhaustion. It's been done better in the past, it's no longer relevant. Art schools treat painting students as though they are pursuing some quaint craft. Anyone with ambition would use video or installation to make art about "real life."

To the beleaguered realist, then, news of a book from Julian Bell could sound like the cavalry. Bell's exhibition reviews in the Times Literary Supplement qualify him as one of the most perceptive and intelligent critics at work today. His recent short monograph on Pierre Bonnard (1994) is written with exquisite poise and acuity. And furthermore, he is himself an exhibiting figurative painter of individuality and accomplishment.

What is Painting?: Representation and Modern Art surveys theories about representation from Moses, the Commandment-giver who prohibits graven images, to Derrida, the Deconstructionist who undermines the very possibility of communication. (The author has included 158 illustrations, 16 in color, as if to put his money where his mouth is.) Bell sets out to offer not a history of art theory, however, but a personal apology for painting.

The main focus of his argument is the evolution of painting over the last two centuries, when it "seemed to part company with the age-old desire for likenesses." Aristotle had established "mimesis" (imitation, likeness) as the fundament for the arts, and it held good from the Renaissance to the dwindling of the Academy in the last century.

Photography, which was invented in 1839, is traditionally blamed for the demise of depiction. In a riveting tour de force of argument, Bell shows that photography "was more of a symptom than a cause of changes in picture making." Indeed, even Sir Joshua Reynolds had his students at the Royal Academy consider how "little and mean" is the information in a camera obscura compared to an artistic depiction of the same scene.

By the time Fox Talbot described photography as "nature's view of nature," the Romantics were intent not on copying nature, but on being nature. In the classical dispensation, the artist copies the handiwork of God. To the Romantic, the imagination is itself divine. The Realism of Courbet is shown to be concerned with the principle of "thingness" rather than the illusion of reality to be had from a camera. Intensity and selection are the prerogatives of a thinking artist. The snapshot parallels Degas in his desire for a "chance, fortuitous personal encounter" rather than directly influencing it.

Bell is at his most passionate and enthralling when he characterizes the intellectual energy of Degas, Bonnard or of Cézanne as a "tantalizing encounter of hungry eyes with elusive nature" that comes away with "a clutch of surface tugs and analogies."

To become a sought-after commodity in the age of mechanical reproduction, a painting had to assert the individuality of its maker. Expression, which became crucial, inevitably pulled away from imitation. The whole notion of "art" became all the more crucial in this context to protect the cherished ideas of authorship and genius.

Bell then sets out to show how notions of "expression" and "art," along with a third piece of baggage that painting picks up in the 19th century, "Modernity," gradually divested painting of its vitality as a means of representation. It is these three categories that end up exhausting painting, Bell argues. But that's Painting with a capital P, that "has for the time being played itself out." The future of painting, Bell seems to say, depends on social contexts, like the artistic competition between Picasso and Braque that created Cubism, or new economic ones, like the market established by Aboriginal painters in Australia.

Just when he starts getting polemical and personal, however, Bell shifts gear. His last chapter, far from a finale, is a cop out. Before, he was busy setting up his own imaginative categories to explain the tensions within painting; now he gets lost in a methodological maze.

The book held such promise, which at lucid moments it began to deliver, of a bold and individual apology for painting, but after starting out with theory looking at painting it ends up with a painter reading theory. Sure, Bell is a very talented explicator (I've never read a more lucid and reader-generous account of structuralism and deconstruction) but that's not much compensation for the sorely needed book he didn't quite write.

There are enough glimpses of good-humored polemic scattered through this book for us to know where his heart really lies, but the reader finds himself grasping at these rather like Cézanne, as Bell describes him, with his "clutch of surface tugs and analogies."