Asked by the editors of the New York Times Book Review … to explain how he became a writer, John Barth gave a surprising answer. "It is my fate and equally my sister's to have been born opposite-sex twins, between whom everything went without saying." But "after circumstances and physical maturation" separated him from his sister, Barth was forced to sail belatedly into society on the changeable winds of language, "talking to the Others, talking to oneself."

Coming from a student or critic, that sort of analysis would undoubtedly seem far-fetched, yet it works as the key to Barth's latest novel, Sabbatical: A Romance. There, Fenwick Turner, the 50-year-old narrator, himself a twin, preaches to his 32-year-old wife, Susan, another narrator, also a twin, that "we literal twins … are each of us the fallen moiety of a once-seamless whole … and our habit of wholeness ought to make us ideal partners, especially for another twin … particularly if our original half falls by the way."

Barth's novel seems deliberately—perhaps too deliberately—built on this psycho-philosophical foundation. As if to prove Fenn's theory, Barth obligingly ensures that Susan's twin sister and Fenn's twin brother do "fall by the way"; the former into drugs and decadence, the latter, fatally, into Chesapeake Bay. This leaves a motley cast of relatives who make brief comic entrances and exits as [Fenwick and Susan] … slowly return to Maryland from a nine-month sabbatical cruise around the Caribbean….

Barth's principal sub-plot is an informal inquiry by the two narrators into the art of novel-writing. As narrators whose conversations are transcribed, Susie and Fenn do not claim to make literary news; they are sailing in the wake of Boccaccio, Chaucer, Conrad, Faulkner. What does distinguish Barth's technique from the strategies of earlier authors is that, unlike most narrators who talk or write to each other, Susie and Fenn normally share a single point of view on a single set of events. Why, then, need their voices be plural at all? Moreover, since they recognize without much debate their literary limitations, those limitations sometimes weaken the novel itself. Temporarily losing his nautical and narrative way at one point, "Fenn is able to shrug and declare that we set our story's ideal course and then sail the best one we can, correcting and improving from occasional fixes in our actual position."

Life, in other words, can throw art off course. But we know that Barth is doing the steering anyway. Despite all the double talk about doubles talking, isn't this book finally and exclusively Fenwick's attempt to write "for the Others" a fictional autobiography that will stand in place of the child Susan considers having, and thereby immortalize their romance? If so, then Susan and the reader may feel, in the end, doubly duped.