The first six episodes of the British Broadcasting Service's extraordinary adaptation of Robert Graves's equally extraordinary novel "I, Claudius," first broadcast in 1976, have at their center not the Emperor Augustus or his successor, Tiberius, but Livia Augusta, wife of the first and mother of the second. As depicted in the script by Jack Pulman and portrayed by the Welsh actress Sian Phillips, Livia is one of history's great villains, whom Matthew Dennison describes in this biography as "a caricature of feminine ruthlessness which remains current despite repeated debunking by classicists and scholars."

This caricature - of "Livia's scheming, her malevolence and, above all, her unbridled maternal ambition and lust for power" - existed nearly two millennia before Phillips's brilliant performance, but the widely watched "I, Claudius," of which a handsomely remastered DVD set is now available, embedded Livia's villainous legend even more deeply in the public mind. Reading Dennison's "Livia" moved me to watch those first six episodes once again, for the fifth or sixth time, and to marvel at the skill with which Phillips brings to life not, perhaps, the historical Livia, but certainly the fictional one.

Which brings to mind the immortal line from John Ford's film "The Man Who Shot Liberty Valance": "When the legend becomes fact, print the legend." The legend of Livia Augusta connects her, in her relentless quest to put her son Tiberius on the Roman throne, "with the deaths of Marcellus, Marcus Agrippa, Gaius and Lucius Caesar, Agrippa Postumus, Germanicus," even Augustus himself, though there is little or nothing that actually establishes those connections beyond accusations made by Tacitus in his "Annals of Imperial Rome," written nearly a century after Livia's death and based on sources of uncertain accuracy.

Obviously, Livia deserves a fairer shake than she has received at the hands of Tacitus, Graves and Pulman. Indeed, it is interesting that the rather perfunctory portrait of her in Suetonius's "The Twelve Caesars," the chief source for Graves's novel, is essentially neutral and in some respects favorable. Graves plainly wanted an eminence grise for his tale, and apparently invented a truly wicked one essentially out of whole cloth, an invention that Pulman seems to have been happy to embroider upon. Dennison, by contrast, believes Livia is entitled to a portrait "more finely balanced, more equivocal - and less indebted to burlesque."

She was born Livia Drusilla in 58 B.C., the daughter of Marcus Livius Drusus Claudianus, the very wealthy son of a powerful, aristocratic family who himself eventually "attained the rank of praetor, one of the Republic's senior magistrates with a powerful judicial role." In 43 or 42 B.C. she married Tiberius Claudius Nero, a marriage that produced two sons, Tiberius and Drusus, but not a lot of happiness or achievement. Then she met Julius Caesar's adopted son, Octavian, a fast-rising star in the imperial hierarchy as the republic moved into its final hours. Even though he had played a role in the death by suicide of her father, she threw everything aside for him, and in January of 38 B.C., a mere three days after giving birth to Drusus, she married him.

By almost all accounts, it was a love match. Suetonius calls Livia "the one woman whom [Octavian] truly loved until his death," but it is difficult to believe that there was no calculation on either side. Marriage among Roman aristocrats "was men's business, managed in order to create alliances that were firstly political and afterwards economic or social." For Octavian, who was a bit of an arriviste, marrying into Livia's rich and important family had obvious benefits, and, for Livia, alliance with Octavian had potential benefits as well, as was proved correct in 31 B.C., when Octavian routed the forces of his rival Mark Antony in the great naval battle of Actium. The engagement led to the suicides of Mark Antony and his lover Cleopatra, and Octavian's seizure of the Roman throne - where, only four years later, he "received at a meeting of the Senate the title he would retain until his death: 'Augustus,' 'revered one.' "

Tiberius was still a boy, but because Augustus's previous marriage had produced only a daughter, Julia, and because of various complexities in relationships among the descendants of Julius Caesar, the line of succession was unclear. What we do know is that Livia badly wanted Tiberius to follow Augustus and that along the way a great many men who stood in his way conveniently dropped dead. Among these were Marcellus, who had married Julia and who died (probably of a "nameless fever"), leaving Augustus "without a son-in-law or the immediate prospect of heirs of his blood, and temporarily lacking any nominated successor from within his family"; Gaius Caesar and Lucius, Augustus's grandsons by his first marriage, the first of unknown causes and the other after a wound; Agrippa Postumus, the last of Augustus's three grandsons; and Germanicus, Livia's promising and popular grandson.

Probably it was all macabre coincidence, but it's easy to see how the legend of Livia emerged from it. Even her partisans readily admit that she was drawn to power, not merely influencing its exercise - as she did regularly in private conversations with Augustus, who valued her intelligence and trusted her counsel - but exercising it herself. As Dennison writes:

"Livia's true 'crime' was not murder but the exercise of power. In a society so assertively masculine that its historians avoided mentioning women save as exemplars of outstanding virtue or vice - or, in the unique but vexed case of Cleopatra, as a ruler in her own right - Livia created for herself a public profile and a sphere of influence. The wife of one princeps ('leading citizen') of Rome, she became the mother of his successor after a series of unforeseeable deaths. In the early years of Tiberius's reign she was acknowledged by several sources as almost his equal in power. Unofficially she was hailed as 'Mother of Her Country.' But any power she exercised was always circumscribed. Assiduously she confined her visible sphere of influence to acceptable, traditionally female areas. That she won public plaudits for her contribution to Roman life was in itself enough to condemn her - in the eyes not only of contemporaries but also of influential later writers."

This judgment obviously is shaped by our own much-altered views about the proper role of women in government and all other places where power is wielded, but it is almost surely accurate. Like Cleopatra, she confounded her contemporaries and was consigned to caricature: Cleopatra as a voluptuary, Livia as a murderess. The more we learn about both women, the more we understand how inappropriate these caricatures really are.

We don't know all that much, though, so too often the biographer or historian is left with little to do except speculate. Dennison is not reluctant to do so. "Perhaps" occurs so often in his narrative that it becomes almost a refrain, along with phrases such as "What form that took we do not know" and "Libo's intention . . . may have been." Et cetera. This is not Dennison's fault, given the paucity of hard evidence, but he certainly is to blame for the endless backing and filling with which his narrative is cluttered. People are dead on one page, alive on the next, dead again a few pages later. Reading "Livia, Empress of Rome" is like punching one's way through a truckload of cotton candy and is no more nutritious. Give me "I, Claudius" any day.


A Biography

By Matthew Dennison

St. Martin's

320 pp. $27.99