Fuentes at His Peak : THE CAMPAIGN<i> By Carlos Fuentes translated by Alfred MacAdam (Farrar, Straus & Giroux:$22.95</i> ; <i> 222 pp.) </i>

During a recent bookstore reading in Florida, Carlos Fuentes, Mexico’s most gifted storyteller and author of such great novels as “Aura,” “The Death of Artemio Cruz” and “The Old Gringo,” spoke of how after finishing “Christopher Unborn,” he wished to be free to write about what he termed “the romantic time”--the early 19th Century.

“The Campaign,” as this new novel is titled, is set in that time, centered on the period from 1810-1815, the five grueling years of Latin America’s most violent revolutionary period.

Our protagonist is Baltasar Bustos. An unlikely hero--he is “plump, myopic, and with bronze-colored curls”--it is Baltasar who sets the plot in motion when, “on the night of May 24, 1810, (he) entered the bedroom of the Marquise de Cabra, the wife of the presiding judge of the Superior Court of the Viceroyalty of the Rio de la Plata, and kidnapped her newborn child. In its place, he put a black baby, the child of a prostitute who had just been publicly flogged.”

Through this action, Baltasar Bustos ignites the fuse to this historical saga of war, unrequited love, loyalty and friendship. Baltasar, the son of a wealthy ranch owner in the desolation of the Pampas, is an idealist and ardent reader of Voltaire, Rousseau and Diderot, whose seductive works Baltasar and his two friends discuss nightly at the Cafe de Malcos in Buenos Aires.

Baltasar is a model of Rousseau’s divided being. He is a porteno --an Argentine living near the river port of Buenos Aires--influenced by social awareness and judicial reform, who, after that crucial moment on the night of May 24, sets out to play the role of the revolutionary democrat. But he is also a person with a private family life, a dying father and an “ugly” sister he’s grown up to hate.

Baltasar’s dilemma is a very human and universal one: love. On the night of the kidnaping, he sees, for a brief and emotionally shattering instant, the infant’s mother, the beautiful and hypnotic Marquise de Cabra, whose “blond, naked, perfumed” image makes a great impact on him, so much so that he sets out to win her forgiveness and love.

His public and personal campaign for justice and redemption takes him through Argentina, Chile, Peru, Venezuela and Mexico--and therefore through the crucial experiences that have formed the psyche of modern Latin America. Throughout the journey, Fuentes teaches Baltasar his lessons of history, such as the one Father Rios, an “enlightened” Jesuit cleric, teaches him: “Would the South American patriots ever understand that without the past they would never be what they so desired: paradigms of modernity? Novelty for its own sake is an anachronism: It races toward its inevitable old age and death. A past renewed is the only guarantee of modernity.”

The historical figures Bolivar and San Martin come alive in this novel, as Baltasar joins their causes. “ ‘I, too, am concerned about justice,’ said San Martin. ‘And wherever we go, we are going to establish free trade, suppress the Inquisition, abolish slavery, and prohibit torture. But you all saw what happened to Castelli and Belgrano in upper Peru. They proclaimed the ideals of the Englightenment to Indians who didn’t understand them and to the Creoles, who didn’t want a permanent revolution. Neither theories nor individuals suffice to achieve justice. We must create permanent institutions. First, of course, we have to achieve independence. Then our headaches will really begin.’ ”

Although this novel has the epic scope of a much larger work, it is a compact tour de force in language and ideas. “The Campaign” is about the importance of time, and what can be learned from its passage. Its narrator is Manuel Varela, who along with Xavier Dorrego “collects” and “keeps” time while their friend Baltasar is away at war. It is safe to say that Varela, a printer and the “writer” of this narrative, is Carlos Fuentes himself, orchestrating historical time to instruct us about our own intricate and difficult present.

With “The Campaign,” Fuentes proves that he remains at the peak of his literary powers, exercising his inventive, remarkable and enduring voice.