Full Idea
There is nothing good about the nature of slavery. The slave can achieve nothing by being virtuous. The master acquires all sorts of bad habits, and is accustomed to behaving with a total lack of moral virtues.
Gist of Idea
Slavery is entirely bad; the master abandons the virtues, and they are pointless in the slave
Source
Baron de Montesquieu (The Spirit of the Laws (rev. 1757) [1748], 15.01)
Book Reference
Montesquieu,Baron de: 'Selected Political Writings', ed/tr. Richter,Melvin [Hackett 1990], p.200
A Reaction
Most slavery of that time took place in colonies, far remote from the moral judgments of the mother country. The temptations of such power over others are far too great for most masters to live virtuously.