Discover the Devil in the detail

This is not a book in the usual sense of that word, but one of a series of stimulating, if superficial, self-teaching manuals published by the J. Paul Getty Museum in Los Angeles that aim to make the armchair art fancier more aware of the hidden meaning behind Old Master paintings. What is likely to sell the book is its stunningly libidinous cover. The Getty has chosen from its own collection, William-Adolphe Bouguereau's 1880 painting of A Young Girl Defending Herself - not very convincingly - against Eros . Its promise of more lusciously painted breasts and saucy buttocks is fulfilled abundantly in the subsequent selection of 365 pages of symbolic nude revelry, nude religiosity and nude moral instruction, which suggests that the book itself is a telling allegory of the principles underpinning modern publishing's relationship with the buying public.

Everything is made easy for the reluctant reader. The illustrations come in four chapters: "Time", "Man", "Space" and "Allegories", with no continuous text, just fact-filled introductory paragraphs to the many, not always obvious, sub-sections. "Man", for instance, includes sub-sections on the Virgin Mary, the Trinity, egg, halo, Satan, monster and zoomorph. The photographic reproduction of paintings from private collections and museums all over the world are brilliantly clear and, while some are comfortingly familiar, most have been chosen to deliver lessons in unfamiliar cultures such as alchemy, neo-Platonic philosophy or the early Fathers of the Church, with occasional ventures into the more modern allegories of Dali, de Chirico, Chagall and Duchamp.

Each illustration is set within wide white margins. Notes printed in these are connected by long arrows to single features in the paintings: a flower, a figure or an animal, which has hidden meanings. This results in a blizzard of startling, unrelated possibilities that leave the reader-scanner wiser or at least healthily confused. Strawberries and cherries are both symbols of lust. Prudence is a quality attributed to snakes. What have pheasants and the boy Narcissus in common? They both fall in love with their own images. A unicorn can symbolise cosmic fecundity, chastity and the death of Christ. The Apostles St John, St Peter, St Mark and St Paul each represent respectively one of the four bodily humours: sanguine John, phlegmatic Peter, choleric Mark and melancholic Paul. Michelangelo's statue of Lorenzo de Medici in Florence may look broodingly handsome, but Lorenzo represents, by subtle details, melancholy and parsimony; apparently he was contemplative and mean.

The author, Matilde Battistini, inclines to be confidently dogmatic. Representation of the Holy Spirit as a human was banned in the 10th century, leaving us with the Dove; St Michael got his suit of armour only in the 14th century; but though Battistini claims that winged angels did not appear until the 4th century AD, the Prophet Isaiah described a six-winged Seraphim very precisely around 500BC: "With twain he covered his face, with twain he covered his loins and with twain he did fly." Those arrows diving down from the margins can sometimes hit the wrong targets. A well-dressed lady in Robinet Testard's 1496-98 The Gaze of Desire miniature is labelled "Venus and Sensual Love", while the stark naked madam on the battlements is labelled "Juno... the choice of the active life", an active life indeed!

Battistini offers one important clarification. The strapping Mercury on Botticelli's Primavera is not picking fruit from the tree. He is chasing away with his caduceus the clouds that could hide the mysteries of love being danced behind him by the Three Graces, one of whom, Chastity, is being initiated naughtily by Beauty and Sensuality - which is the book's overriding theme.

Timothy Mowl is reader in architectural and garden history, Bristol University.