55% sureLots of sources credit Niels Bohr with this, and they agree with each other. The book or the speech it first came from hasn't turned up yet.
What turned up
Reported from Bohr's 1920 meeting with Heisenberg (Discussions about Language, 1933, via later secondary works) — recollection chain, not Bohr's own writing
Occasion
1920 · talking with Werner Heisenberg about how to describe atoms
Sources checked
en.wikiquote.orgChecked using claude-sonnet-5, 20 August 2026Wikiquote sourced section, citing Discussions about Language (1933)
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