Montesquieu

Montesquieu treated law as a natural phenomenon, shaped by climate, custom, economy, and history, and set out to understand it rather than merely to praise or condemn. The Spirit of the Laws compares governments across the world and across time, and argues that liberty survives only where power is divided against itself, the legislative, executive, and judicial each checking the others. The framers of the American constitution read him closely. He began, slyly, with the Persian Letters, letting fictional travelers from Isfahan expose the absurdities of Paris with an outsider's innocent eye.