The show has subtitled itself "A Personal Voyage," but rarely have we seen so much of Sagan's biography wrapped up in the narrative. This important conceit – that our narrator is human – helps connect us as viewers, allowing us to map ourselves onto Sagan's story that is, in parts, our own. We can each recall a moment when we were young when the world grew in size, when the world showed itself to be far grander than our limited experience. Developing a shared experience is crucial: it allows us a foothold in the greater thematic parallel in this episode, that we ourselves have experienced a similar growth in understanding of the world as a species.

The parallel narrative between Sagan's childhood and humanity's understanding of the cosmos is subtle and finely crafted. Consider: Sagan's world when he was young was small – just a few blocks in the Bensonhurst section of Brooklyn. He could see stars at night. These piqued his curiosity, driving him beyond the confines of his small universe and into a new neighborhood containing a library. Our ancient human ancestors also thought that their world was small, that it was unique, that all the gods and movements of the stars in the sky were focused on them. But the stars called out to us, pulling us beyond our known world towards greater knowledge, finding ourselves within "something much grander" than we ever would have guessed.

We are given a tantalizing tour of this pivotal moment in human history with a thrilling tour of ancient greek scientists and assorted achievements. The ancient greeks created the foundations of modern science, drama, linguistics, rhetoric, and politics. Their speculations (particularly the wrong ones) would deeply influence the western world for the next 2500 years. Not bad for a loose collection of city-states over the course of a few centuries.

Sagan argues that this "glorious awakening" grew from a practical response to problems faced by semi-isolated merchant-cities. A heady mix of ideas, beliefs, and treasure simmered in a region far away from established, oppressive powers. Sagan expands on this idea in the book version of Cosmos, saying that given enough time, science would likely emerge in many civilizations, but it had to happen first somewhere.

You can hear the excitement in Sagan's voice as he spells out possibly the most important idea in human history:

"It was argued that the universe was knowable. Why? Because it was ordered, because there are regularities in nature that permitted secrets to be uncovered. Nature was not entirely unpredictable, there were rules that even she had to obey. This ordered and admirable character to the universe was called cosmos."

This is what its all about. That's the key to every benefit of the modern world. The universe is knowable. Without any predictability, we would live in a terrifying chaos, utterly subject to forces beyond our understanding, we could only make desperate attempts to placate them.

But if there are universal laws that even nature obeys, there's no reason to adhere to prescriptive rules set out by priests to appease gods, because the gods aren't the ones running the show. This lifts a heavy burden: disasters, plagues, and other blights are no longer the result of our own actions. We are freed from placating capricious beings who may, at any time, upset and alter the behavior of the world. How liberating this is. How powerful.

But to many people this is can be more frightening than the gods themselves. If nature is a physical consequence of basic laws governing behavior of matter and energy, then humans are sidelined. There's no placating nature; she is merciless. Some would rather chose a chaos that they may have the ability to persuade than a cosmos in which they are mere bystanders.

Of course, this first era of proto-science was temporary. Many ideas were suppressed and lost. What we know about them come through second-hand accounts or tattered scraps of parchment. Out of the same fertile ground grew the idea of the division between the natural world and thought. Plato and Aristotle's ideas of a sullied natural world, separate from the distant perfection of the heavens, dominated western thinking for thousands of years. Not until Kepler did observation once again meet theory.