My mother made me a scientist without ever intending to. Every other Jewish mother in Brooklyn would ask her child after school: So? Did you learn anything today? But not my mother. “Izzy,” she would say, “did you ask a good question today?” That difference — asking good questions — made me become a scientist.
As quoted in "Great Minds Start With Questions" in Parents Magazine (September 1993).
I think physicists are the Peter Pans of the human race. They never grow up, and they keep their curiosity.