In Book 6 of Virgil's Aeneid, the hero travels to the underworld to meet with his father, Anchises. When Aeneas finally encounters his father, his father shows him some of the future leaders of the city he will be helping to establish. Before Anchises turns to the figure of Claudius Marcellus, he makes the following comment:
Others (I can well believe) will hammer out bronze that breathes
with more delicacy than us, draw out living features
from the marble: plead their causes better, trace with instruments
the movement of the skies, and tell the rising of the constellations:
remember, Roman, it is for you to rule the nations with your power,
(that will be your skill) to crown peace with law,
to spare the conquered, and subdue the proud.’
(A.S. Kline translation)
Anchises' comment here is one of the most famous passages in the Aeneid because it essentially defines what Romans are supposed to do as a nation. In contrast to the Greeks, who may be more skilled as artisans, rhetoricians, or astronomers, the mandate of the Romans will be to rule other nations, to establish the ways of peace through the establishment and enforcement of law, and finally to show mercy to those who ask for it, while crushing into the dust those who refuse to submit to Rome's authority (e.g., the Carthaginians in 146 BCE).
The last line of this mandate is of particular importance to Aeneas, who, at the end of Aeneid 12, has to decide whether or not to spare Turnus, who is begging Aeneas to spare his life. Thus, Aeneas has to choose whether to spare the conquered or subdue the proud, either one of which are applicable to Turnus at the end of the poem. Thus, Aeneas' choice is a choice similar to one's that many Roman leaders would face and which some leaders still face today.