The first two, representation and separation of powers, were distinctly modern inventions: both were logically derived from Lockean natural-rights theory and its corollary theory of consent.
The last principle, however, what Adams called the "triple equipoise," was hardly a modern invention.
With its roots in the theory and practice of classical antiquity, the so-called mixed regime rested on an entirely different theoretical foundation.
Adams's great theoretical achievement was to reconcile those hitherto discordant doctrines.
Shunned by aristocratic old-world diplomats, Adams worked tirelessly, employing what he called "militia diplomacy"; he raced back and forth between Paris and The Hague, breaking all the rules of diplomatic etiquette, and pounding on doors until he was listened to.
Eventually, he succeeded in convincing the Dutch Republic to recognize American independence in 1782—and he negotiated critical loans with Amsterdam bankers.
From Adams's perspective there were two main problems that must be addressed by all republican constitution-makers.
The first was to find some kind of constitutional device by which to neutralize the vices, but also to draw out and up the talents of the exceptional few.
After twice serving as vice-president under George Washington, the American people elevated Adams to the presidency in 1796.
His greatest accomplishment as president was to navigate the nation through the political storm known as the "Quasi-War." In what Mc Cullough calls the "bravest" act of his political career, Adams (consulting no one) incurred the wrath of Republicans and his own Federalist party by sending a peace mission to France.