Hamilton claims that modern political science has discovered institutional improvements — representation, separation of powers, legislative balances, judicial independence, and enlarged territorial extent — that make stable republics possible for the first time.
Federalist No. 9 (Hamilton)
The science of politics, however, like most other sciences, has received great improvement. The efficacy of various principles is now well understood, which were either not known at all, or imperfectly known to the ancients.