This is the great day. This is the greatest event in all the history of the human race, up to this time. That is — today is New Year's Day of the Year One. If we don't change the calendar, historians will do so. The human race — this is our change, our puberty rite, bar mitzvah, confirmation, from the change of our infancy into adulthood for the human race. And we're going to go on out, not only to the Moon, to the stars; we're going to spread. I don't know that the United States is going to do it; I hope so. I have — I'm an American myself; I want it to be done by us. But in any case, the human race is going to do it, it's utterly inevitable: we're going to spread through the entire universe.

In a live interview with Walter Cronkite of CBS News, on the day of the first moonwalk (20 July 1969). - Robert A. Heinlein: In Dialogue With His Century, Volume I (1907–1949): Learning Curve (2010)