We succeeded in taking that picture [of Earth from deep space], and,
if you look at it, you see a dot. That's here. That's home. That's us...
on a mote of dust, suspended in a sunbeam.
The earth is a very small stage in a vast cosmic arena. Think of the
rivers of blood spilled by all those generals and emperors so that in
glory and in triumph they could become the momentary masters of a
fraction of a dot...Our posturings, our imagined self-importance, the
delusion that we have some privileged position in the universe, are
challenged by this point of pale light.
Our planet is a lonely speck in the great enveloping cosmic dark. In
our obscurity -- in all this vastness -- there is no hint that help
will come from elsewhere to save us from ourselves. It is up to us.
It's been said that astronomy is a humbling, and I might add, a
character-building experience. To my mind, there is perhaps no better
demonstration of the folly of human conceits than this distant image
of our tiny world. To me, it underscores our responsibility to deal
more kindly and compassionately with one another and to preserve and
cherish that pale blue dot, the only home we've ever known.

Carl Sagan (1934-1996), Reflections on a Mote of Dust(an image of Earth taken by Voyager 1 from the edge of the Solar System)