In 1972, the great Argentine writer Jorge Luis Borges published a short story called "The Other," in which his elderly self, seated on a bench in Cambridge (the alma mater of Serena Frome, the protagonist of Sweet Tooth), bumps into his younger self. The two versions of Borges engage in a dialogue from which each comes away disconcerted by the differences between them, a device that is used by Borges to reflect on the disparate selves that we inhabit in the course of our lives. McEwan replicates a similar but fleeting moment in the course of his narrative. Toward the end of the book, as Serena is making her way through the crowd at Victoria station, she has a sudden vision: "I happened to glance to my right, just as the crowd parted, and I saw something quite absurd. I had a momentary glimpse of my own face, then the gap closed and the vision was gone." Sweet Tooth follows the same logic as Borges, for McEwan, now sixty-four and the author of more than a dozen books, uses this novel to reflect back on his early career.On the surface, the plot seems to belie this strategy. Set in the 1970s, its first-person narrator is a young woman who, after graduating from Cambridge with a degree in mathematics, is recruited by MI5. Although women are usually handed MI5's lowliest tasks, Serena is given a break: she is assigned to an operation called Sweet Tooth, which provides covert funds to authors who have an established anti-communist bias. As such, Serena recruits Tom Haley, a budding young writer with whom she soon begins an affair. In this layer of the story McEwan provides a searching and sometimes hilarious examination of artistic integrity in relation to the state, a subject that resounds in a number of directions: the rise of a neoconservative ideology that has seen cuts to arts funding over the last four decades, the grounding of Sweet Tooth in the real-life precedent of the CIA's funding of the magazine Encounter, and even Haley's choice of Spenser's Faerie Queene as the topic of his doctoral thesis, since Spenser's work is an allegorical epic poem that bears a similarly complicated relationship to the politics of the Elizabethan age. Indeed, one might argue that the Faerie Queene, rather than any spy thriller, is McEwan's biggest clue as to how to read this particular dimension of the novel (although I suspect that Spenser will somehow not see a dramatic spike in sales as a result).Concealed within this story is a recurrent set of in-jokes about McEwan and his early career, expressed through the character of Tom Haley. As part of her background research, for instance, Serena reads Haley's published stories, which bear strong similarities to the style and themes of McEwan's early fiction. Like Borges, McEwan treats his younger self with a mixture of appreciation and amusement, establishing a deliberately ambiguous relationship with those earlier works. On the surface, he asks us to admire them, but underneath he seems to be smirking at their now-apparent youthful enthusiasm. McEwan also gives Haley many of his own biographical features, from his lanky frame to his home university of Sussex. Again, this quasi-portrait is undercut with an Austen-like irony that is easy to miss the first time through, most notably McEwan's repeated insistence on Haley's being a "swordsman" whose mastery in bed is commented on at every turn by Serena. It is difficult - and therefore deeply humorous - to work out whether McEwan is engaging in sexual boasting by proxy, or whether these moments arise from self-deprecating humor, or whether, like in Austen, the line between the two has become so blurry that it is no longer possible to judge the difference. Either way, careful readers of the novel, especially those who are reading it for a second time, should have wonderful time picking out these shades of ambiguity.Sweet Tooth has wrongly been billed as a spy novel in the vein of, say, John le Carré, or even a thriller in the mold of McEwan's earlier novel The Innocent, but that is not what this book is about at all. Instead, it asks searching questions about the value of literature to both the educational and political vitality of a society. Serena is a voracious but poor reader: she reads purely for the surface entertainment of a book, for instance, while missing the subtle underlying meanings of the text. As such, she avoids poetry and experimental prose, refusing to grapple with difficult works in what McEwan intimates is a symptom of a larger failure to engage in true critical thinking. Books are in danger, he warns us, of becoming as useless as the defunct telephones in Haley's dystopian novella: "Without a telephone system, telephones are worthless junk." Without a critical reading audience, McEwan implies, works of literature, including Sweet Tooth, are "worthless junk," toys that are reduced to lowly entertainment when they could be used for so much more.To conclude, if you have never read a book by Ian McEwan, then DO NOT start with this one. The reason is simple: Sweet Tooth is in many ways a literary retrospective, an oblique reflection by the author back on the origins of his career. As such, if you haven't read any early works by McEwan - especially In Between The Sheets - and don't know anything about his life, you will miss a great deal of the logic and rich humor embedded in this novel.