David Hilbert... was perhaps the most absentminded man who ever lived. He was a great friend of the physicist James Franck. One day when Hilbert was walking he met Franck and he said, "James, is your wife as mean as mine?" Well, Franck was rather taken aback by this statement and didn't quite know what to say, and he said, "Well, what has your wife done?" And Hilbert said, "It was only this morning that I discovered quite by accident that my wife does not give me an egg for breakfast. Heaven knows how long that has been going on."