We must remember that there are many men who, without being productive, are anxious to say something important, and the results are most curious.

[Man muß bedenken, daß unter den Menschen gar viele sind, die doch auch etwas Bedeutendes sagen wollen, ohne produktiv zu sein, und da kommen die wunderlichsten Dinge an den Tag.]

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

Sprüche in Prosa: Maximen und Reflexionen [Proverbs in Prose: Maxims and Reflections] (1833) [tr. Saunders (1893), “Literature and Art,” #415]
    (Source)

From Wilhelm Meister's Journeyman Years (1829).

(Source (German)). Alternate translations:

It must be borne in mind that there are many men who, without being productive, yet want to say something significant; and thus the most curious things are brought to light.
[tr. Rönnfeldt (1900)]

One has to remember that there are quite a lot of people who would like to say something significant without being productive, and then the most peculiar things see the light of day.
[tr. Stopp (1995), #497]