No one would talk much in society, if he only knew how often he misunderstands others.

[Niemand würde viel in Gesellschaften sprechen, wenn er sich bewußt wäre, wie oft er die andern mißversteht.]

Johann Wolfgang von Goethe (1749-1832) German poet, statesman, scientist

Elective Affinities [Die Wahlverwandtschaften], Part 2, ch. 4, “From Ottilie’s Journal [Aus Ottiliens Tagebuche]” (1809) [Niles ed. (1872)]
    (Source)

(Source (German)). Alternate translation:

We would not say very much in company if we realized how often we misunderstand what others say.
[tr. Hollingdale (1971)]