MANY GOOD NOVELS take place from within a character's mind. Most of Crime and Punishment, for example, is seen through Raskolnikov's eyes. And while Virginia Woolf's To the Lighthouse is told in the third person, there is no real narrator, causing the reader to slip from mind to mind with no perceptible voice to bridge the gaps. All that floating free sometimes can give readers mental seasickness. To avoid this, most authors use plot for ballast. The plot structures the thoughts, the thoughts give added resonance to the "real events." In A.N. Wilson's Wise Virgin, however, the balance breaks down, and plot and ideas end up in a predictable and boring rut.

Wise Virgin's plot is about the balance between promiscuity and monasticism, and between innocence and cynicism. Witness the title: to modern lascivious ears, "wise virgin" sounds like an innocent losing here naivete. But in the "Treatise of Heavenly Love," the pet project of a medievalist named Giles Fox, the phrase refers to the Gospel parable of the wise and foolish virgins. Those who have "kept burning that holy light of virginity in their lamps can present themselves spotless to their Lord and Lover," says the thirteenth-century sermon, but their concupiscent comrades will be damned by their "fleshly lusts and carnal appetites."

All this medieval rhetoric gives the book a very clever structure. Louise Agar has spent her 26 failure-ridden years believing in the distant past. But now the "Lord and Lover" has become her employer Giles, instead of Christ. The Treatise fascinates Giles, too--not its ideas, but its language. After losing his sight and his first two wives. Giles hires Louise as a research assistant. His sorrows, his grouchy promiscuity, and his insecurities as a scholar leave him totally unprepared for her chaste, almost religious adoration. Unless he can deal with his miserable past, his budding love affair is doomed to flounder in misdirected lusts.

Giles Fox's half of this story consists more of his melancholy memories than with his bizarre relationship with Louise. In transporting us to Giles' past, the narrator spends a painfully large amount of space telling us what Giles used to feel, rather than scenes he once saw:

While his contemporaries fell in love or attached themselves to religion or politics, he stood self-consciously aloof, knowing that his teachers admired his linguistic ability and than a very small circle of friends enjoyed his contemptuous altitude toward life. With what predictable withering epigrams he had managed to dismiss those fools who thought the world was worth saving by a change in its political system: With what equally brief violence of phrase he had dealt with the ideas of the God-squad!

All this is very clever indeed, but goes nowhere toward making us feel what Giles felt. We are not able to picture the young Giles' cynicism at Cambridge from the narrator's sarcasm. Giles himself does not seem to have learned anything from his experience either. We long for anecdote, gasping with renewed interest when a crumb of plot is revealed. Wilson may have done this intentionally is make us feel how petty Giles Fox's life is. If so, the idea fails, because the result is overblown in its melodrama and moreover-tedious to read.

THESE PRECARIOUS BALANCES of cleverness and emotion, introspection and detail, work much better in the secondary plot. Seventeen-year-old Tibba Fix's portion overflows with the security of books and imaginary sex surrounding every bright, shy teenager. Her thoughts are full of real objects--food, pianos, imaginary lovers: even her memories of childhood are more poignant than her father's because she remembers real events: slamming doors, a policeman's arrival.

Even though the narration treats Tibba's fantasies and eventual blossoming love-life ironically, it at least gives us something substantive to grab hold of. The picture of Tibba that we get from her father's musings is quite pathetic: it is not until we catch her pretending to be Virginia Woolf that we start chuckling at her. Her scenes with Piers Peverill, head boy at her uncles's boarding school, are delightful ("you were very good at kissing. Fox, but I really want to have it off with you as soon as possible"): Peverill, a charmer who gets away with every kind of mischief, neatly complements Tibba's seriousness.

Wilson manages to make most of the minor characters both real and fun. Giles' sister Margaret and her husband Monty are a sketch of the English public school house-master and his wife, but since they know that they are, a bit of realism manages to creep into the joke. Louise's mother, whom we meet only briefly, cheers characters and reader alike, combining dishpan-hands and a low-class accent with friendliness and a talent for the piano that she even reaches out to a blind man.

But all the fun and clever characters in the book do not seem to balance with Giles' weighty gloom. It is hard to see the world, so to speak, through a blind man's eyes, and hard to make funny stories with happy endings out of morose ideas. Wise Virgin's cleverness just cannot buoy up its hero's dead weight.