We begin (and end) in one of Carl Sagan's favorite virtual environments from the original series: the Library of Alexandria. Sagan used the Library as a cautionary tale about what can be lost when a civilization is careless with its knowledge, but Tyson uses it as an inspirational story.
Tyson views the Library as a triumph, because it represents our civilization's ongoing quest to gather and maintain stores of knowledge. And Tyson has a theory about the social process that goes into making a library.
The acquisition of knowledge begins with admitting our own ignorance. We profit nothing by pretending to have answers we don't have. No one human is perfect and no period in history is free of prejudice. The purpose of science is to factor out our biases and assumptions and to provide a basis for separating fact from conjecture, theory from hunch and reason from delusion. It is this self-correcting mechanism that makes science not just another worldview, not just another bag of speculation among many.
From Alexandria, we move once again into the history of geology and astrophysics, from the first globes developed by Martin Behaim in the fifteenth century, through the discovery the supernova by the awesomely named astrophysicist and indie rock mascot Fritz Zwicky, through the discoveries of dark matter by Vera Rubin and dark energy in the 1990s by the equally awesomely named High-Z Supernova Search Team.
In my interview with Dr. Tyson, I asked him why he has said that dark matter and dark energy should be renamed "Fred and Wilma." According to Tyson, the terms "dark matter" and "dark energy" are just "code words for our ignorance." Calling them "matter" and "energy" gives the impression that we have some idea what these forces actually are when the truth is, right now, we haven't got a clue.
From Fred and Wilma, we move on to the Voyager missions' exploration of the outer solar system. Carl Sagan was a member of the imaging team for the Voyager mission. As Voyager 1 passed the orbit of Neptune, Sagan convinced NASA to turn the craft around and take a photograph of the distant and minuscule Earth, which he famously dubbed "The Pale Blue Dot."
Tyson ends by replaying Sagan's original monologue about this distant cosmic selfie. Sagan plainly states that looking back on the Earth from this vantage makes it impossible to imagine that this entire place, this cosmos, was made with us in mind. We are recent arrivals on a small speck floating around an unremarkable star in a commonplace galaxy. Imagining ourselves to be the special purpose of creation isn't mere hubris, it's dangerous delusion.
For all our vaunted self-importance, for all our assurance that this massive, incredible place was made just for us, there is no evidence that anyone is coming to save us from ourselves. It is for us, huddled together on this humble blue speck in the vast cosmic ocean, to develop systems of knowledge and thought that provide us with the tools we need to survive in a wondrous, beautiful and completely indifferent universe.
We are responsible for maintaining our home and establishing our cosmic citizenship. For while we may not be the special, hand-designed paragons of all creation we imagine ourselves to be, we are something far, far more precious: we are the cosmos coming alive, waking up and getting to know itself.
Taking the night's sky as a metaphor, Tyson notes that the vast majority of what we see around is us shrouded in darkness and obscurity. Only a few pinholes glow like candles in the night. When we deny the light, when we close our minds to science and reason, we do far more than deprive ourselves of truth, we literally waste the universe's time.