What does it mean?
You only really notice how your own language works when you compare it with another one.
Who said it?
Johann Wolfgang von Goethe: German poet, playwright and scientist (1749–1832). Source: Maxims and Reflections (1833).
Language learning– Johann Wolfgang von Goethe, Maxims and Reflections (1833)
“Those who know nothing of foreign languages know nothing of their own.”