The delight of social relations between friends is fostered by a shared attitude to life, together with certain differences of opinion on intellectual matters, through which either one is confirmed in one’s own views, or else one gains practice and instruction through argument.

[Le plaisir de la société entre les amis se cultive par une ressemblance de goût sur ce qui regarde les moeurs, et par quelques différences d’opinions sur les sciences: par là ou l’on s’affermit dans ses sentiments, ou l’on s’exerce et l’on s’instruit par la dispute.]

Jean de La Bruyère (1645-1696) French essayist, moralist

The Characters [Les Caractères], ch. 5 “Of Society and Conversation [De la Société et de la Conversation],” § 61 (5.61) (1688) [tr. Stewart (1970)]
    (Source)

(Source (French)). Alternate translations:

The pleasure of Society amongst Friends is cultivated by a likeness of Inclinations, as to Manners; and a difference in Opinion, as to Sciences: the one confirms and humours us in our sentiments; the other exercises and instructs us by disputation.
[Bullord ed. (1696)]

The Pleasure of Society amongst Friends, is cultivated by a likeness of Inclinations, as to Manners, and by some difference in Opinion, as to Sciences: The one confirms us in our Sentiments, the other exercises and instructs us by Disputation.
[Curll ed. (1713)]

The pleasure of social intercourse amongst friends is kept up by a similarity of morals and manners, and by slender differences in opinion about science; this confirms us in our sentiments, exercises our faculties or instructs us through arguments.
[tr. Van Laun (1885)]