Montesquieu

A large num­ber of sla­ves has dif­fe­rent effects under various govern­ments. It is no bur­den in des­po­tic govern­ment : the poli­ti­cal sla­very esta­bli­shed in the body of the state makes civil sla­very hardly per­cep­ti­ble. Those who are cal­led free men are hardly more free than those who have not that title ; and inas­much as the lat­ter, as eunuchs, eman­ci­pa­ted men, or sla­ves, have almost all busi­ness in hand, the condi­tion of a free man and that of a slave are very simi­lar. It is the­re­fore almost indif­fe­rent there whe­ther few or many peo­ple live in sla­very.

But in mode­rate sta­tes it is very impor­tant that there not be too many sla­ves. There poli­ti­cal liberty makes civil liberty pre­cious, and he who is depri­ved of the lat­ter is also depri­ved of the for­mer. He sees a happy society of which he is not even a part ; he finds secu­rity esta­bli­shed for others, and not for him­self ; he sen­ses that his mas­ter has a mind that can expand, and that his own is cons­tantly for­ced to hum­ble itself. Nothing pla­ces a per­son clo­ser to the condi­tion of beasts than to see free men all the time and not be free one­self. Such per­sons are natu­ral ene­mies of society and in quan­tity would be dan­ge­rous.

Therefore we should not be sur­pri­sed that in mode­rate govern­ments the state has so often been per­tur­bed by slave revolts, and that this has hap­pe­ned so rarely1 in des­po­tic sta­tes.

The revolt of the Mamluks was a particular case : it was a corps of militia that usurped the empire.