BOOK REVIEW / In The Frame: A victim of anonymity: 'A Victim of Anonymity: The Master of the Saint Bartholomew Altarpiece' - Neil MacGregor: Thames & Hudson, 6.95 pounds

THE GREAT Biography Debate is a hardy perennial in the world of books. Everyone is familiar with the refrain: should we know about an artist or writer's life, and if so how much, and does it matter, and if so in what way? Often, we're childishly contented with an anecdote: the squeak on Jane Austen's dining-room door that warned her when someone was coming, or Leonardo da Vinci's habit of buying caged birds to set them free. We don't much care if these stories are true; they just serve to humanise the minds whose works might otherwise fill us with too much awe. There are those who gulp biographical detail for its own sake, and those who like to use it to infer intricate occult meaning from a work. And there are a few who maintain that knowledge of the life actually interferes with appreciation of the work, because it tempts us to treat art as a mere expression of personality, a sort of psychological thumb-print on the universe.

In A Victim of Anonymity: The Master of the Saint Bartholomew Altarpiece (Thames & Hudson pounds 6.95), Neil MacGregor, the director of the National Gallery in London, takes the art/life debate back to first principles, by examining what happens to the reputation and perception of an artist when even his name is unknown. (I am tempted to say his or her name, but in the case of this late-15th century German painter, I'm afraid that historical likelihood is against me.)

His text is short - it was last year's Walter Neurath Lecture, given each spring in memory of Thames & Hudson's founder - and even in black and white the reproductions of the few works attributed to the Bartholomew Master are fine. The Master is, sadly, typical of his contemporary countrymen in his anonymity: the German room of the National Gallery's Sainsbury Wing contains not a single picture that is signed, and only three that can be attributed with any confidence to named artists. This makes a stark contrast to the lavishly documented Italians, who usually signed their pictures prominently, and often also left contracts, records or details of the process of their works. 'We know how much the eggs cost that went to make tempera for the San Pier Maggiore Altarpiece,' Neil MacGregor writes - yet it's hard even to be sure of the Bartholomew Master's nationality.

The battier biographical obsessions obviously operate as much in the world of art criticism as in lit crit: there are people, Neil MacGregor tells us, who claim to be able to tell from Goya's late work that the artist was deaf. This is just the kind of thing that sets up the Great Divide on biographical fact: one view is that this piece of knowledge (Goya's deafness) allows an immeasurably richer appreciation; the other will say that it is all nonsense, and that anything can be 'significantly' interpreted in the light of anything else, if you put your mind to it. They are probably both right, and both wrong.

The author is too responsible to indulge in playing the Goya-was-deaf game, and heroically refrains from speculating that the Bartholomew Master had freckles, or played chess, or kept a cat. But one of the charms of his monograph is that it tacitly invites us to play the game for ourselves, and the pictures are more than rich enough to provide plenty of fuel. Was the Master very short, for instance? Would that explain his habit of chopping off his background landscapes with a curtain of brocade behind the figures, showing only the tops of trees and hills, which suggests the eye-line of a small child in front of a high window? MacGregor soberly points out that this technique arose after early paintings revealed a problem with the middle distance . . . Aha] so he might have been short-sighted . . . It could go on indefinitely.

The question, though, is whether the absence of 'real' information, of even a name, matters. Neil MacGregor, as his title makes clear, thinks it does, very much. An anonymous work is bound to suffer some degree of undervaluation and neglect; an artist stripped of his name becomes 'a construct of connoisseurship', and 'for modern art history, dominated as it is by the availability of written sources, little short of a catastrophe'.

Rotten luck for the Master, and to some extent for scholars - but there are advantages. We can look at these pictures freshly, unencumbered by preconception. There is a fascination in anonymity (the sobriquet of the Master of the High Foreheads, for instance, makes his tiny ceramic medieval Mekons more interesting), and there's a heroism in the message of such unknown artists, transmitted to us down the centuries only by the undeniable signature of their genius. It is precisely the lack of information which makes us realise how much we do 'know' about the Bartholomew Master, and - here's the lesson - how much the work can let us know. We can't mistake his sensuality, his humour, the robust physicality that makes elegant, even flirtatious couples of his saints, his passion for texture, his visual wit and playfulness. He loves shoes. He is theatrical; a slight show-off . . . and so on. Such knowledge suddenly becomes more precious than anecdotes about squeaky doors and caged birds. And, as Neil MacGregor ends his fine, lightly textured and provoking lecture by saying, 'If paintings have no documentation . . . we are forced to consider them primarily in terms of how they speak to us now. For a work of art, that is perhaps not a bad thing.'

(Photograph omitted)