Русско-англо-русский юридический словарь

Later Polybius in his analysis of the Roman Constitution used the concept of aristocracy to describe his conception of a republic as a mixed form of government, along with democracy and monarchy in their conception from then, as a system of checks and balances, where each element checks the excesses of the other. (Wikipedia)

Machiavelli argued that Rome’s mixed form of government was best and he has influenced political theory down to this day. (Britannica Blog)