A Brilliant Juggling Act 
 Science fiction, fantasy, and dystopia are not normally my favorite genres. But I do respond to intelligence and culture and the ability to dance across boundaries as though they didn't exist. And I am a sucker for a good story well told with interesting characters, all guided by a strong moral sense that is not too simplistic. Iain Pears enfolded me in mystery and delight from the first few pages of his new novel and held me in his spell for five hundred more. In the first two chapters alone, he sets up the perfect working of an ideal world, then turns it inside out to show the mechanics, then enters it again from a totally different direction. Read only 20 pages, and just see if you are prepared to stop there. 
 Imagine a landscape. Bathed in sunshine, sweet-smelling from the gentle shower that fell overnight then stopped as dawn broke. A dense grove of holm oak stands at the foot of a hill, damp with the drops of soft-sounding water which leave the ground moist but firm underfoot. 
 The opening lines, limpid and lovely. Perhaps a bit over the top, too self-consciously poetical? Indeed, and that is the point. A few pages later, we get a middle-aged scholar, Henry Lytten, reading his fantasy to a group of other amateur novelists in an Oxford pub much as his friends Tolkien and CS Lewis used to do. "Bit of Ovid in there," one of them remarks, and indeed he is right; the holm oak gives it away, that tree that seems a staple of classical landscapes but you don't encounter anywhere else. Lytten, with a thorough classical education, is recreating the Arcadia of Greek and Roman pastoral, that ideal world populated by amorous shepherds and shepherdesses, where the occasional visit by a demigod or nymph wouldn't be anything out of the ordinary. Professionally, Lytten is an expert in Sir Philip Sidney, whose own Arcadia was the prose equivalent of Ovid for the Elizabethans. He is also a lover of Shakespeare, who created many Arcadias of his own; later parts of the story so closely recreate the scenes in the Forest of Arden from As You Like It that the novel might easily qualify as one of the retellings in the Hogarth Shakespeare series. 
 But it is so very much more. The literary references--like the scientific, mathematical, and philosophical ones that will come in later--are there for the adult reader, but the story is one that you could give to a young teen of either sex in full confidence that they would not put the book down until they were finished. In those opening pages, a young shepherd named Jay encounters what he takes to be a fairy, the sudden appearance in a cave of a girl of about his age, smiling radiantly in a halo of light. In the next chapter, we meet Rosie Wilson, Lytten's fifteen-year-old neighbor who comes in occasionally to feed Professor Jenkins, his malevolent cat. Poking around in the basement to hunt for her absconding charge, Rosie walks through an old Victorian iron pergola that is being stored down there, and sees a young shepherd boy gazing up at her with awe. 
 The best Pears book I have read before this was 
 The Dream of Scipio 
 , a tour-de-force set in the Midi that juggled three time-periods: the late Roman Empire, the Avignon papacy, and Vichy France. Pears has three distinct worlds here too: Lytten's utopia that he calls Anterworld; a chilling future dystopia that we shall meet in the next chapter, where vast populations huddle in huge industrial complexes in a blighted landscape; and Lytten's own period, the early 1960s, when postwar reconstruction and Cold War fears battle for the future of society, where visions of a welfare-state utopia seem less real than nuclear holocaust. But unlike the separate and substantial chapters in Scipio, the three worlds here interpenetrate all the time; the entire novel is a brilliant juggling act. Anterworld, for example, does not exist merely in Lytten's head; it can be accessed physically, as we have seen. And not merely from the present, but from the future. 
 For in Chapter 3, in a sealed-off research facility on the Isle of Mull, we meet Angela Meerson, a "psychomathematician" who has invented a machine for accessing alternate universes. This makes her a hot property for the fascist oligarchs who run this dystopia, since it seems to open access to unlimited resources of food and space. But Meerson realizes that, so far from going to other universes, it merely transports the experimenter to other periods within one's own. In other words, a time machine. This may sound crudely Wellesian, but Pears is actually quite subtle in his philosophical exploration of how past may affect future and vice-versa, a theme that Tom Stoppard also explores in his dramatic masterpiece, 
 Arcadia 
 , which I assume was an influence here. Yet he also shows that, barring major catastrophes, it is quite difficult to change history. Meerson runs a computer simulation that shows that, although things might have been different for a few years had Nixon defeated Kennedy in 1960, history would nonetheless have reverted to the same course within two decades. Anyway, Angela Meerson escapes with the secret of her machine by traveling through time herself, becoming a good friend of Henry Lytten, in whose basement she stores various parts of her equipment. 
 There are other themes too. Lytten, for example, has had what is called "an interesting war," and still does occasional work for British intelligence. But I did not find the Le Carre elements as successful as the rest. And while I was always interested in the hunt for Angela Meerson and the secret of her machine, in the end this all took second place to the scenes in Anterworld, which opened out and took on a life of their own, going far beyond their Arcadian or Arthurian origins. Although I have spent a lot of time here describing all the things that intrigued me as an adult, my greatest enjoyment came when I returned to my thirteen-year-old self and settled down to this magnificent romance of young lovers, ancient rituals, and the pursuit of justice. I hated to see it end.