Source, in full
Attributed to Einstein by physicist John Archibald Wheeler in John Horgan's article "Profile: Physicist John A. Wheeler, Questioning the 'It from Bit'". Scientific American, pp. 36-37, June 1991. Reprinted here after Wheeler's death.
More quotes by Albert Einstein
A happy man is too satisfied with the present to dwell too much on the future.
Try to become not a man of success, but try rather to become a man of value.
Life is like riding a bicycle. To keep your balance you must keep moving.
Attribution
Quote text and notes from Wikiquote: Albert Einstein (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.