There’s a deceptively simple reason “Earthrise” is perhaps the most iconic photograph in human history: it puts all of  human history in perspective. All of our troubles, all of our accomplishments, everything the human race has ever done is right there in that one photo. As NASA astronaut Edgar D. Mitchell put it, “You develop an instant global consciousness…You want to grab a politician by the scruff of the neck and drag him a quarter of a million miles out and say, ‘Look at that, you son of a bitch.'” Earthrise is widely credited as the genesis of the environmental movement.

Few words can adequately summarize the significance of this cosmic perspective, but Carl Sagan’s attempt may be one of the best. In the video above, Carl Sagan reads a passage from his book, Pale Blue Dot, a recording that was recently remastered and featured in Neil deGrasse Tyson’s version of COSMOS. His words describe the photo below, taken by the Voyager 1 space probe from 6 billion kilometers (3.7 billion miles) away.

The photo was actually at the behest of Sagan, who encouraged NASA to turn the probe around and get another picture of cosmic perspective.

To me, Sagan’s famous speech — he always spoke with such lyrical clarity — was the best part of the new COSMOS, and stands as the written equivalent of Earthrise. Look again at that dot. That’s here. That’s home. That dot is a humbling reminder that the Earth is all we have. If we don’t try to preserve it, if we don’t get its current human-caused fever in check, that’s it.

Images: NASA