Of Laws in Relation to the Principles Which Form the General Spirit, Morals, and Customs of a Nation
14. What are the natural Means of changing the Manners and Customs of a Nation. We have said that the laws were the particular and precise institutions of a legislator, and manners and customs the institutions of a nation in general. Hence it follows that when these manners and customs are to be changed, it ought not to be done by laws; this would have too much the air of tyranny: it would be better to change them by introducing other manners and other customs.
Thus when a prince would make great alterations in his kingdom, he should reform by law what is established by law, and change by custom what is settled by custom; for it is very bad policy to change by law what ought to be changed by custom.