Source, in full
As quoted in John Von Neumann: The Scientific Genius Who Pioneered the Modern Computer, Game Theory, Nuclear Deterrence, and Much More (2016) by Norman Macrae, p. 352 in response to Oppenheimer's 'destroyer of worlds' quote.
More quotes by John von Neumann
With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.
Young man, in mathematics you don't understand things. You just get used to them.
Attribution
Quote text and notes from Wikiquote: John von Neumann (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.