Bruni believed that liberty makes virtue possible, and without virtue there can be no glory. In his 1428 oration in praise of Nanni Strozzi, Bruni says:
Praise of monarchy has something fictitious and shadowy about it, and lacks precision and solidity. Kings, the historian [Sallust] says, are more suspicious of the good than of the evil man, and are always fearful of another’s virtue. Nor is it very different under the rule of a few. Thus the only legitimate constitution of the commonwealth left is the popular one, in which liberty is real, in which legal equality is the same for all citizens, in which pursuit of the virtues may flourish without suspicion.Bruni held that cities must be must be governed according to justice if they are to become glorious. He says that justice is impossible without liberty. Here’s his comment on political system in 15th century Florence:
Therefore, under these magistracies this city has been governed with such diligence and competence that one could not find better discipline even in a household ruled by a solicitous father. As a result, no one here has ever suffered any harm, and no one has ever had to alienate property except when he wanted to. The judges, the magistrates are always on duty; the courts, even the highest tribunal is open. All classes of men can be brought to trial; laws are made prudently for the common good, and they are fashioned to help the citizens. There is no place on earth where there is greater justice open equally to every- one. Nowhere else does freedom grow so vigorously, and nowhere else are rich and poor alike treated with such equality. In this one can discern Florence’s great wisdom, perhaps greater than that of other cities.
(Quoted in The Earthly Republic: Italian Humanists on Government and Society, edited by Benjamin G. Kohl and Ronald G. Witt)A Republican constitution is must for safeguarding the freedom of the people, according to Bruni.