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