Since the publication of his 1986 collection Less Than One, Joseph Brodsky has continued to develop his mastery of an idiosyncratic form that defies literary genre. Brodsky's prose pieces superficially resemble familiar or critical essays, but they lack the clarity and analytic pointedness one expects from those forms. Willfully opaque and meandering, they often leave more music and texture than the sense of an argument understood. Their structures invisible, Brodsky's nonfiction writings veer often into aphorism and apostrophe, as they mine autobiographical and philosophical veins tenuously related to the topic at hand.

So it is with Watermark, a slim volume whose intent seems not so much to propound a thesis as to complicate and deepen an intellectual relationship, creating dazzling plays of metaphor and paradox in the process. Brodsky's is a murky, beautiful, frustrating work, which draws the reader closer to his subject without attempting definitive judgements, or really any judgement about it at all. Simultaneously absorbing and elusive, it is a literary hybrid that may be best appreciated if thought of as a kind of thematic prose-poem, or a dramatic monologue, rather than an essay.

Venice, as Mary McCarthy commented, is a phenomenon about which "the rationalist mind has always had its doubts." Her own novella-lengthessay on the subject, Venice Observed, however, constitutes an effort to see what the rationalist mind can do with the city after all. Brodsky, on the other hand, goes with the flow of the place. There is little to say about Venice as urban curiosity that has not been said already, and he is not interested in matching art-historical or architectural wits with Ruskin and Bernard Berenson (though he does steal a line from Prince Charles, blaming modern architects for doing "more harm to the European skyline than any Luftwaffe"). Rather, Brodsky uses the city as departure points for a series of watery meanderings. "If I get sidetracked," he writes, "it is because getting sidetracked is literally a matter of course here and echoes water."

Those anticipating a kind of exalted travel book, the kind a Nobel laureate might toss as a bouquet to his fans, will be disappointed. Brodsky fails to even note most of those sights beloved of tourists and neglects as well the city's politics, economics, cultural life, even its currently consuming questions of conservation. Nor does he make an effort to capture its indigenous social milieu, which is largely closed-off to short-term visitors. McCarthy made much of the materialism and matter-of-factness of the Venetians. But Brodsky's only discussion of the city's habitants is his brief aside that "no tribe likes strangers, and Venetians are very tribal."

The sole Venetian characters in his book appear almost as ghosts. The first is a minor aristocrat, "the umpteenth," who throws a party crashed by the author in a mildewed palazzo. Brodsky's discursus on the gala neglects the guests for the putti, and it wanders off into a meditation on time and space. The only other local in his account is not a native Venetian at all, but an American, Olga Rudge, Ezra Pound's widow, whose flat Brodsky visits with his friend Susan Sontag. Rudge feeds him tea and "garbage" and reminds him of the old CP members he dealt with as a young dissident in the Soviet Union. But she too is an anachronism, less meaningful to Brodsky than the lifeless stones—which bring him closer to the ethereal realm he seeks.

What, we might ask, draws him to the city? Brodsky credits his visits to "visual reasons." He calls Venice "the city of the eye," and again a place where the body "starts to regard itself as merely the eye's carrier." But physical beauty, though often noted, seems a happenstance, rather than that which the poet seeks in his sojourns. Brodsky is purposeful in limiting his visits to winter, during which the days are short and the clouds hang low. This is not just a strategy for avoiding German tourists. It is during this "abstract season," as he calls it, when things are paradoxically at their most real. Venice, where Brodsky has been traveling each winter for almost twenty years, becomes a way for this self-described "cardiac cripple" to transcend the confines of the body. Venice in winter is for him a head-clearing experience, a catalyst for deeper thoughts.

Brodsky's most pungent descriptions are often metaphorical inversions: concrete things articulated through comparison to incorporeal ones. Arriving for the first time, he writes: "The boat's slow progress through the night was like the passage of a coherent thought through the subconscious." Opening a window on Sunday, his room is flooded with a "pearl-laden haze, which is part damp oxygen, part coffee and prayers." Through the book, Venice itself appears as a dream or a reflection rather than a solid presence. And the author is a dreamer within a dream. Venice is a city to which for years he has been returning "or recurring in it, with the frequency of a bad dream." This conceit helps explain the book's apparent lack of direction. If dreams were a genre, Brodsky cracks, "their main stylistic device would doubtless be the non sequitur."

Thus the author seems as much a connoisseur of the idea of Venice as of the city itself. He describes the place almost as if it were one of Italo Calvino's magical, invisible cities. The only thing better for his purposes than a city built on water would be a city built on air, as he paraphrases Hazlitt. The Venice he loves is both the real city and the unreal one that lends itself to transcendent thoughts. The deepest theme of his essay is the passage from the real to the unreal, from the physical to the metaphysical.

Brodsky's distinctive, unidiomatic English, which reveals and conceals at the same time, is particularly appropriate to his task. Unlike Nabokov, whose adoptive language aimed to dazzle with its fluent precision, Brodsky's remains contentedly foggy. When a term sticks in his head, he repeats it more times than conventional style allows, and he relies heavily on figures of speech—"not to say," "not to mention," "better yet"—to connect his peregrinations. At the same time, he is wonderfully inventive, devising collective nouns like "a parthenon of candles" or the "kremlin of drinks" he imagines upon a table. This vernacular, too, reflects his theme; his meanings shimmer just beneath the cloudy surface of his writing.

It is in this context that Brodsky's title begins to make sense. At one level, his is a book about the actual Venice, a city which is marked by water, both historically and aesthetically. But at another level, Brodsky is writing about the watermark familiar to stamp collectors, a translucent image imbedded in paper, which becomes visible to the naked eye only when it is held up to the light or wetted. Venice for him is such an emblem; it is a physical dimension containing a metaphysical essence; a place where what goes unseen becomes visible, upon immersion in the author's own depths.