Full Idea
Louis XIII was made extremely uneasy by the law that enslaved all the negroes in his colonies. But when told that this was the most efficacious way of converting them, he gave his consent.
Gist of Idea
French slavery was accepted because it was the best method of religious conversion
Source
Baron de Montesquieu (The Spirit of the Laws (rev. 1757) [1748], 15.04)
Book Reference
Montesquieu,Baron de: 'Selected Political Writings', ed/tr. Richter,Melvin [Hackett 1990], p.203
A Reaction
That is a spectaculary bad advert for giving an established religion a leading role in society. It is relevant to the upbringing of children, as well as to slaves.