“Dictator,” by Robert Harris. (Knopf)

In a prefatory note to his new novel, the last installment of a trilogy, Robert Harris describes the Roman statesman Cicero as having lived through “arguably — at least until the convulsions of 1933-45 — the most tumultuous era in human history.” Cicero was a pivotal figure of the time: the man who both saved the Roman republic from being hijacked by Catiline and his fellow conspirators and also inadvertently buried the republic by placing his trust in the young Octavian, soon to be Emperor Augustus. Cicero’s was a life rich in gravitas and drama, and Harris depicts it with erudition and élan.

“Dictator” begins with Cicero on the run from his arch-enemy, the tribune Clodius, a friend and supporter of Catiline, whose fall Cicero had helped bring about by skewering the traitor in scathing orations that are still de rigueur for students of Latin. Slandered by Clodius and harried by his thugs, Cicero goes into exile — a condition for which, according to our narrator, the slave Tiro, he was “of all the men I ever knew . . . the least equipped by temperament.”

Before long, however, Cicero is back in Rome, trying to salvage his reputation and regain his confiscated property by outsmarting his rich, powerful and unscrupulous foe. The canny Cicero probes for a weakness and finds it. Always careful to cultivate the populace, Clodius has donated a statue purporting to represent the goddess Liberty. Cicero learns that it was wartime booty of scandalous origin. To the merriment of all Rome, he makes the point in one of his trademark sallies: “So this is [Clodius’s] idea of Liberty — a courtesan’s likeness, erected over a foreign tomb, stolen by a thief and set up again by a sacrilegious hand!” Needless to say, advantage to Cicero.

Clodius is far from finished, though; he will bedevil Cicero again and again. If he is a one-dimensional villain, it’s probably no fault of Harris’s — the Pulchers (the family name) seem to have been ancient Roman precursors of the Borgias. More subtle are the characterizations of other major figures: Julius Caesar, whose political judgment dissipates as the fame and power accruing from his consummate generalship go to his head (he seems to believe in his own divinity); Cato, whose rectitude tends to spill over into righteousness, which is a form of selfishness; and Octavian, poised and single-minded beyond his relatively few years — he is a teenager when his and Cicero’s paths first cross — and surely the best student of politics the older man ever had.

Tiro, a literate slave who actually existed — he invented a shorthand that survives in the abbreviations &, etc., N.B., i.e. and e.g. — narrates with the affection of an underling whose master treated him as a near-equal and eventually freed him. He tells us what Cicero said about changing residences (a frequent occurrence): “I have put out my books and now my house has a soul.” And he paraphrases the master’s approach to death: “A human being can only train for death by leading a life that is morally good; that is — to desire nothing too much; to be content with what one has; to be entirely self-sufficient within oneself, so that whatever one loses, one will still be able to carry on regardless; to do none harm; to realize it is better to suffer an injury than to inflict one; to accept that life is a loan given by Nature without a due date and that repayment may be demanded at any time; that the most tragic character in the world is a tyrant who has broken all these precepts.”

As that passage shows, the older, wiser Cicero withstood the loss of power and influence that might have staggered another man by putting his fertile mind to work. In his last years, he wrote philosophical books, such as “On Friendship” and “On Duties,” that are still worth reading 2,000 years later.

Harris seems to have mastered every telling aspect of the world and the conflicts he dramatizes, from the excitement occasioned by each new account of Caesar’s far-off triumphs (“whenever his Commentaries were posted . . . crowds would gather and remain there all day reading of his exploits,” to the strategy for conferring executive clemency (above all, make the grantor look good).

The new novel’s predecessors — “Imperium,” which centered on Cicero’s lawyerly campaign against Verres, the corrupt governor of Sicily; and “Conspirata,” which featured Cicero as the statesman who defended the republic against Catiline — made ancient history exciting. “Dictator” goes even further, imparting wisdom and consolation. In his Ciceronian trilogy, Robert Harris has richly evoked and given shape to a “most tumultuous era in human history.”

Dennis Drabelle is a former contributing editor of Book World.

Dictator

By Robert Harris

Knopf. 385 pp. $26.95