People here argue about religion interminably, but it appears that they are competing at the same time to see who can be the least devout.
– Charles de Montesquieu, Lettres Persanes (1721) No. 46

Religious wars are not caused by the fact that there is more than one religion, but by the spirit of intolerance…the spread of which can only be regarded as the total eclipse of human reason.
– Charles de Montesquieu, Lettres Persanes (1721) No. 85

There are only two cases in which war is just: first, in order to resist the aggression of an enemy, and second, in order to help an ally who has been attacked.
– Charles de Montesquieu, Lettres Persanes (1721) No. 95

Republics end through luxury; monarchies through poverty.
– Charles de Montesquieu, De l’Esprit des Lois (1748) VII, Ch. IV

But constant experience shows us that every man invested with power is apt to abuse it, and to carry his authority as far as it will go.
– Charles de Montesquieu, De l’Esprit des Lois (1748) XI, Ch. 4

When the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty; because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws, to execute them in a tyrannical manner.
– Charles de Montesquieu, De l’Esprit des Lois (1748) XI, Ch. 6

Useless laws weaken the necessary laws.
– Charles de Montesquieu, De l’Esprit des Lois (1748) XXIX, Ch. 16

If I knew of something that could serve my nation but would ruin another, I would not propose it to my prince, for I am first a man and only then a Frenchman…because I am necessarily a man, and only accidentally am I French.
– Charles de Montesquieu, Pensées et Fragments Inédits de Montesquieu (1899)