The tree of the knowledge of good and evil grew in the Garden of Eden; what grew in the garden of King Alcinous, as described in the Odyssey, were all manner of fruit trees. This orchard-garden was watered by two springs: an important consideration in a Mediterranean climate (the kingdom of Alcinous is widely held to have been Corfu). It was, however, no ordinary place; in this magical garden the fruit remained on the trees, ripe for plucking, and never spoiled or fell to the ground, while the vines bore both flowers and fruit simultaneously. Homer's imagined earthly paradise is thus a place of fertility and eternal lack of corruption, rather than of original sin and hence loss. Wise people, the ancient Greeks.

At first their garden seems to reflect a world of ease and luxury from which the narrator feels himself to be excluded; he does not dare accept Micol's invitation in the days of their childhood when she sits on the wall and instructs him to climb it and join her in the garden. Later, when they are in their early twenties, he is able to enter through the main gate, a guest now at Micol's tennis parties during a long, hot, bittersweet autumn. They wander through the garden together, yet his love for her remains unrequited: there is always an underlying feeling that he is an outsider looking in at a world he will never be able to inhabit.

What is more, the novel is set in the Italy of the late 1930s and both the narrator and the Finzi-Contini are Jewish, so that from the beginning of the book the reader knows that the young man's pain will soon be overlaid by suffering of an unimaginably greater kind: the other 'gardens' referred to repeatedly throughout the novel are those of the Jewish cemeteries of Venice and Ferrara. Micol and her family, Bassani tells us, never returned from the concentration camp to which they were sent, her trees were all cut down for firewood in the winter of 1943... In retrospect the garden remembered thus comes to represent a lost world of innocence and sunlight, a time when - in spite of the gathering menace - life was still somehow safe and predictable.

Mediterranean gardens, by the very nature of the contrast between hot, bright light and deep shade, tend necessarily to be more dramatic than their counterparts in temperate climates. And another fictional Italian garden, this time in Henry James' short story The Last of the Valerii, is from the beginning not benign. The theme - as in many of James' novels - is that of the consequences of marriage between a worldly but impoverished European aristocrat and an innocent (and often naive) young American woman with money. In this story what the wife must deal with is her husband's pagan obsession with a Roman statue of Juno, of extreme beauty, disinterred during archaeological excavations in the garden. (Her solution in the end is to have the statue buried again.)

fragrance somehow seems to carry with it a whiff of corruption - tuberoses, for example, or overblown roses: in the midst of life we are in death, they seem to say. The Leopard, by Giuseppe Tomasi di Lampedusa, an exquisite novel heavy with the scent of faintly squalid baroque splendour, opens with the daily recital of the Rosary in a princely Sicilian household. When the Prince walks in his garden to savour the half-hour between evening prayers and dinner, we are told that it was "exhaling scents that were cloying [...] like the aromatic liquids distilled from the relics of certain saints".

This garden is a place where "every sod seemed to exude a yearning for beauty soon muted by languor", a place whose "seclusion gave it the air of a cemetery". And indeed, a month previously, other nauseatingly sweetish odours had alerted the family to the presence of an unknown young soldier "wounded in the skirmish with the rebels" (this is May 1860 and Garibaldi has just landed in Sicily), who had dragged himself into the garden to die, all alone, under a lemon tree. The boy's body is described in the same sort of detail as the garden: there is a matter-of-fact sensuality in death as in life, a De Profundis for the soldier's soul is added to the evening Rosary while from a grove beyond the wall comes "an erotic waft of early orange-blossom".

Only the Prince, whose reflections on a changing world fill this novel, continues to be haunted by the corpse and to worry that "the person dying should know, or at least feel sure that someone knows, for whom or for what he is dying". The mood of this Sicilian garden introduces the reader to the tone of languorous decay that permeates the whole book.

These fictional uses of the garden tell me something about its power as an imaginative key with which the writer may unlock feelings and responses in his readers. Naturally enough, they leave quite unanswered the question of why people make gardens in the first place.