“Again time passed. In one of the remoter galaxies a supernova flamed, and on a rocky, barren world a small living thing squirmed experimentally—and to mankind the one event was just as important as the other.”

Source: Ready Player One

Source: The Tale of the Body Thief

The Lords and the New Creatures: Poems (1969), The Lords: Notes on Vision

Source: Mrs. Mike

Source: The Garden That I Love: Second Series (1907), p. 4.

Words said when Armstrong first stepped onto the Moon (20 July 1969) One Small Step, transcript of Apollo 11 Moon landing https://www.hq.nasa.gov/alsj/a11.step.html. In the actual sound recordings he apparently fails to say "a" before "man" and says: "That's one small step for man, one giant leap for mankind." This was generally considered by many to simply be an error of omission on his part. Armstrong long insisted he did say "a man" but that it was inaudible. Prior to new evidence supporting his claim, he stated a preference for the "a" to appear in parentheses when the quote is written. The debate continues on the matter, as "Armstrong's 'poetic' slip on Moon" at BBC News (3 June 2009) http://news.bbc.co.uk/2/hi/science/nature/8081817.stm reports that more recent analysis by linguist John Olsson and author Chris Riley with higher quality recordings indicates that he did not say "a".
Variant: That's one small step for a man, one giant leap for mankind.

The Pragmatics of Patriotism (1973)
Context: Many short-sighted fools think that going to the Moon was just a stunt. But the astronauts knew the meaning of what they were doing, as is shown by Neil Armstrong's first words in stepping down onto the soil of Luna: "One small step for a man, one giant leap for mankind."

Introduction.
Pippa Passes (1841)