We should strive only to think and speak rightly, without seeking to win others over to our own taste and opinions; that is too great an undertaking.

[Il faut chercher seulement à penser et à parler juste, sans vouloir amener les autres à notre goût et à nos sentiments; c’est une trop grande entreprise.]

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

The Characters [Les Caractères], ch. 1 “Of Works of the Mind [Des Ouvrages de l’Esprit],” § 2 (1.2) (1688) [tr. Stewart (1970), “Of Books”]
    (Source)

(Source (French)). Alternate translations:

We must only endeavour to think and speak justly our selves, without aiming to bring others over to our taste and sentiment; We shall find that too great an enterprize.
[Bullord ed. (1696) "Of Polite Learning"]

We must only endeavour to think and speak justly our selves, without aiming to bring others over to our Taste and Sentiments; that would be too great an Enterprize.
[Curll ed. (1713), "Of Works of Wit and Eloquence"]

We must only endeavour to think and speak justly ourselves, without aiming to bring others over to our Taste and Sentiments; that would be too great an Enterprize.
[Browne ed. (1752), "Of Works of Genius"]

We should only endeavor to think and speak correctly ourselves, without wishing to bring others over to our taste and opinions; this would be too great an undertaking.
[tr. Van Laun (1885)]