Oh, dense intelligence. I suspect that it was Batavian (i.e. from the Netherlands-Batavia).
O crassum ingenium. Suspicor fuisse Batavum.
Original text (Latin)
More quotes by Erasmus
Do not be guilty of possessing a library of learned books while lacking learning yourself.
I am a citizen of the world, known to all and to all a stranger.
A speech comes alive only if it rises from the heart, not if it floats on the lips.
The most disadvantageous peace is better than the most just war.
Attribution
Quote text and notes from Wikiquote: Erasmus (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.