The heart's eternal vow has run up against the world's finite terms. The confrontation occurs near the end of the first chapter, which recounts Dr. Urbino's last day on earth and Fermina's first night as a widow. We then flash back 50 years, into the time of cholera. The middle chapters follow the lives of the three characters through the years of the Urbinos' marriage and Florentino Ariza's rise at the River Company, as one century ticks over into the next. The last chapter takes up again where the first left off, with Florentino, now, in the face of what many men would consider major rejection, resolutely setting about courting Fermina Daza all over again, doing what he must to win her love.

IN their city, throughout a turbulent half-century, death has proliferated everywhere, both as el colera, the fatal disease that sweeps through in terrible intermittent epidemics, and as la colera, defined as choler or anger, which taken to its extreme becomes warfare. Victims of one, in this book, are more than once mistaken for victims of the other. War, ''always the same war,'' is presented here not as the continuation by other means of any politics that can possibly matter, but as a negative force, a plague, whose only meaning is death on a massive scale. Against this dark ground, lives, so precarious, are often more and less conscious projects of resistance, even of sworn opposition, to death. Dr. Urbino, like his father before him, becomes a leader in the battle against the cholera, promoting public health measures obsessively, heroically. Fermina, more conventionally but with as much courage, soldiers on in her chosen role of wife, mother and household manager, maintaining a safe perimeter for her family. Florentino embraces Eros, death's well-known long-time enemy, setting off on a career of seductions that eventually add up to 622 ''long-term liaisons, apart from . . . countless fleeting adventures,'' while maintaining, impervious to time, his deeper fidelity, his unquenchable hope for a life with Fermina. At the end he can tell her truthfully - though she doesn't believe it for a minute - that he has remained a virgin for her.

So far as this is Florentino's story, in a way his Bildungsroman, we find ourselves, as he earns the suspension of our disbelief, cheering him on, wishing for the success of this stubborn warrior against age and death, and in the name of love. But like the best fictional characters, he insists on his autonomy, refusing to be anything less ambiguous than human. We must take him as he is, pursuing his tomcat destiny out among the streets and lovers' refuges of this city with which he lives on terms of such easy intimacy, carrying with him a potential for disasters from which he remains safe, immunized by a comical but dangerous indifference to consequences that often borders on criminal neglect. The widow Nazaret, one of many widows he is fated to make happy, seduces him during a night-long bombardment from the cannons of an attacking army outside the city. Ausencia Santander's exquisitely furnished home is burgled of every movable item while she and Florentino are frolicking in bed. A girl he picks up at Carnival time turns out to be a homicidal machete-wielding escapee from the local asylum. Olimpia Zuleta's husband murders her when he sees a vulgar endearment Florentino has been thoughtless enough to write on her body in red paint. His lover's amorality causes not only individual misfortune but ecological destruction as well: as he learns by the end of the book, his River Company's insatiable appetite for firewood to fuel its steamers has wiped out the great forests that once bordered the Magdalena river system, leaving a wasteland where nothing can live. ''With his mind clouded by his passion for Fermina Daza he never took the trouble to think about it, and by the time he realized the truth, there was nothing anyone could do except bring in a new river.''

IN fact, dumb luck has as much to do with getting Florentino through as the intensity or purity of his dream. The author's great affection for this character does not entirely overcome a sly concurrent subversion of the ethic of machismo, of which Garcia Marquez is not especially fond, having described it elsewhere simply as usurpation of the rights of others. Indeed, as we've come to expect from his fiction, it's the women in this story who are stronger, more attuned to reality. When Florentino goes crazy with live, developing symptoms like those of cholera, it is his mother, Transito Ariza, who pulls him out of it. His innumerable lecheries are rewarded not so much for any traditional masculine selling points as for his obvious and aching need to be loved. Women go for it. ''He is ugly and sad,'' Fermina Daza's cousin Hildebranda tells her, ''but he is all love.''

And Garcia Marquez, straight-faced teller of tall tales, is his biographer. At the age of 19, as he has reported, the young writer underwent a literary epiphany on reading the famous opening lines of Kafka's ''Metamorphosis,'' in which a man wakes to find himself transformed into a giant insect. ''Gosh,'' exclaimed Garcia Marquez, using in Spanish a word we in English may not, ''that's just the way my grandmother used to talk!'' And that, he adds, is when novels began to interest him. Much of what come in his work to be called ''magic realism'' was, as he tells it, simply the presence of that grandmotherly voice.

Nevertheless, in this novel we have come a meaningful distance from Macondo, the magical village in ''One Hundred Years of Solitude'' where folks routinely sail through the air and the dead remain in everyday conversation with the living: we have descended, perhaps in some way down the same river, all the way downstream, into war and pestilence and urban confusions to the edge of a Caribbean haunted less by individual dead than by a history which has brought so appallingly many down, without ever having spoken, or having spoken gone unheard, or having been heard, left unrecorded. As revolutionary as writing well is the duty to redeem these silences, a duty Garcia Marquez has here fulfilled with honor and compassion. It would be presumptuous to speak of moving ''beyond'' ''One Hundred Years of Solitude'' but clearly Garcia Marquez has moved somewhere else, not least into deeper awareness of the ways in which, as Florentino comes to learn, ''nobody teaches life anything.'' There are still delightful and stunning moments contrary to fact, still told with the same unblinking humor - presences at the foot of the bed, an anonymously delivered doll with a curse on it, the sinister parrot, almost a minor character, whose pursuit ends with the death of Dr. Juvenal Urbino. But the predominant claim on the author's attention and energies comes from what is not so contrary to fact, a human consensus about ''reality'' in which love and the possibility of love's extinction are the indispensable driving forces, and varieties of magic have become, if not quite peripheral, then at least more thoughtfully deployed in the service of an expanded vision, matured, darker than before but no less clement.

It could be argued that this is the only honest way to write about love, that without the darkness and the finitude there might be romance, erotica, social comedy, soap opera - all genres, by the way, that are well represented in this novel - but not the Big L. What that seems to require, along with a certain vantage point, a certain level of understanding, is an author's ability to control his own love for his characters, to withhold from the reader the full extent of his caring, in other words not to lapse into drivel.