Montesquieu

Human laws made to speak to the mind must give pre­cepts and not gui­dance ; reli­gion, made to speak to the heart, should give much gui­dance and few pre­cepts.

When, for exam­ple, it pres­cri­bes rules, not for the good but for the best, not for what is good but for what is per­fect, it is appro­priate that they be gui­dance and not laws, for per­fec­tion does not regard the uni­ver­sa­lity of men or of things. Besides, if it is laws, there will have to be an infi­nite num­ber of others to see that the first ones are obser­ved. Celibacy was coun­se­led by Christianity ; once it was made into a law for a cer­tain order of men, new ones were requi­red every day to oblige the men to observe that one.1 The legis­la­tor wea­ried ; he wea­ried society to get men to exe­cute by pre­cept what those who love per­fec­tion would have exe­cu­ted as gui­dance.

See Bibliothèque des auteurs ecclésiastiques du Ve siecle, vol. V by Mr. [Louis] Dupin.