Montesquieu

Among peo­ples, we must dis­tin­guish jea­lousy of pas­sion from jea­lousy of cus­tom, ethos, and laws. The first is an ardent, consu­ming fever ; the lat­ter, cold but some­ti­mes fear­some, can go hand in hand with indif­fe­rence and scorn.

The one, which is an abuse of love, is born of love itself. The other depends solely on the ethos and man­ners of the nation, on the coun­try’s laws, its morale, and some­ti­mes even its reli­gion.1

Jealousy is almost always the effect of the phy­si­cal force of the cli­mate, and it is the remedy for that phy­si­cal force.

Mohammed recommended to his partisans that they keep their wives. A certain imam said the same thing upon dying, and Confucius preached that doctrine no less.