A review by zmb
The Spirit of the Laws by Montesquieu

4.0

Montesquieu is clearly more modern than Aristotle (Politics) or Cicero (On the Republic), and while you'd expect 2000 years to buy you something, it remains high praise. Still, he's a half century before the French and American revolutions and that shows, too. His discussion of different types of government owes a lot to the Greeks and Romans, but he definitely brings in his own ideas which are more in tune with our own.

I also found his discussion of the evolution of Frankish laws (particularly trial by combat) and the establishment and dynastic changes of the French monarchy particularly fascinating, even though they mostly amount to a 200 page footnote of the main text. (I suppose you could also call them a case study of the laws and how they depend on the form of government.)