Lucius Ampelius, Liber Memorialis
“ On Constitutions There are three kinds of constitution: rule by kings, by the best men, and by the People. For some are accustomed to be under the control of kings, like Seleucia of the Parthians, or under the control of a Senate, like Massilia in Gaul, or they rule themselves, like the Athenians. There is a fourth kind, which the Romans invented, in order to make a single system from these three: for the consuls have the power of kings, the highest matters of public debate take place in the Senate, and the populace have the power of voters. ”
