Full Idea
Berlin says there were three great turning points: after the death of Aristotle (when Greek schools focused on the inner life of individuals, instead of as social beings), Machiavelli's division of political and individual virtues, and Romanticism.
Gist of Idea
The great moments are the death of Aristotle, Machiavelli, and Romanticism
Source
report of Isaiah Berlin (The Sense of Reality [1996], p.168-9) by Peter Watson - Ideas Intro
Book Reference
Watson,Peter: 'Ideas: from fire to Freud' [Phoenix 2006], p.6
A Reaction
I have the impression that Machiavelli introduced a new hard-boiled ethics, which dominated the sixteenth century, but in the seventeenth and eighteenth century they fought back, and Machiavellianism turned out to be just a phase.