This impels a pessimistic (re)reading of imperium sine fine in the Aeneid, informed (as all readings are) by our historically conditioned experience. Like many other optimistic prophecies in the epic, Jupiter’s speech in Book 1 distorts the truth for rhetorical motives — here, to reassure Venus that Aeneas’ descendants will survive. Juno ultimately extracts a superseding promise that the Trojans’ bloodline and culture will be subsumed into the local Italian population, rendering their victory Pyrrhic indeed. By the end of the poem, Rome’s city walls have yet to be built. Instead, at the very moment of victory, Aeneas loses control over his emotions and buries his sword in his defeated opponent’s body. This final act of violence, triggered by the memory of a dead friend, unleashes the fury that Roman rule was supposed to contain, in Jupiter’s ideal vision:

The dreadful gates

whence issueth war, shall with close-jointed steel

be barred impregnably; and prisoned there

the heaven-offending Fury, throned on swords,

and fettered by a hundred brazen chains,

shall belch vain curses from his lips of gore.

From its earliest meaning, as the power of life and death over others, imperium existed only within confines: anything otherwise would be tyranny or anarchy. Aeneas’ final (ab)use of this power further reminds us that imperium over others ultimately depends on rule over one’s self. In both cases, a lack of restraint, boundaries, or goals — the darker connotations of imperium sine fine — would have struck many Romans as dangerous indeed.

Aeneas’ remembering rage at the end of the epic puts him into parallel with the Trojans’ enemy Juno, whose own remembering rage (memorem iram) drove much of the plot. Jupiter’s final question to his wife — “what end will there be?” — might apply just as well to the modern US as we, too, struggle not to “become the evil we deplore.” On a negative reading, imperium sine fine connotes the ability to use military force over others without end or purpose — even without a goal-post (one meaning of meta in the prior line). The 9/11 terrorists at least had a target in their sights. It is increasingly hard to imagine how, when, or with what success the US pursuit of vengeance can end as it extends from figures like Saddam Hussein and Osama bin Laden to ill-discerned targets the world over, taking countless innocent lives in the process.

As the opening monologue of HBO’s Rome suggests, it is easier to topple foreign kings than to lead a representative government:

Four hundred years after the last king was driven from the city, the Republic of Rome rules many nations, but cannot rule itself.

One unintended consequence of America’s expanding global imperium, like Rome’s, has been a creeping expansion of the chief executive’s powers over the state and its citizens. From Caesar to Caligula to Caracalla, Roman history shows that as autocrats break free of legal and ethical constraints, their own self-control (or lack thereof) becomes the measure of their rule. This places terrifying destructive potential within reach of the tail that wags the dog of Trump’s America. The head of the world’s most powerful body politic is no longer expected to articulate, much less advance, any coherent goals or policies (another sense in which American imperium increasingly lacks finibus).

Indeed, Trump shows no compunctions against embroiling the world in nuclear warfare out of ego-driven, Twitter-fed rage. In Roman culture, the foldable curule chair that accompanied magistrates symbolized the rights and responsibilities of imperium; a sphere signified Rome’s collective ambition to bestride the world like a colossus, by the grace of her gods and the might of her leaders. In their place, the nuclear football that trails Trump symbolizes his autarchic, Senecan potential to ignite universal conflagration on a whim with “fire, fury, and frankly, power, the likes of which the world has never seen.”