The theme of this week's episode of Cosmos is illumination, both literal and metaphorical. Carl Sagan famously called science a "candle in the dark," illuminating the human mind with the knowledge imparted by evidence-based reasoning.
Tyson's story of light begins with Mo Tsu, the ancient Chinese philosopher who discovered the principles of camera obscura. Mo Tsu, Tyson tells us, used his intellect to battle all forms of darkness. He was a military genius who used his prowess to prevent violence and make peace, he preached universal love, an end to poverty and government by the people.
Mo Tsu was popular, but a few centuries after his death, his writings were banned by Emperor Chin, along with the writings of Confucius and other free thinkers. The chilling effect of Emperor Chin's philosophy, called "legalism," establishes a pattern of darkness that can only be banished by Sagan's candle.
Tyson's second master of light is Ibn al Hasan, who discovered that light travels in straight lines. Al Hasan lived in a time when the Muslim world was developing advanced notions of math and science and thrived on curiosity and intellectual freedom. To this day, our science is a parade of Al's, from algebra to algorithms, alchemy to alcohol, all derived from Arabic sources. Al Hasan himself suggested error-correcting mechanism for filtering our prejudices out of our quest for the truth.
The contrast with the modern Arabic world couldn't be more profound. It stands as a warning to our own culture that there is no scientific end zone, no final achievement, no moon landing or split atom that guarantees our safety from the darkness of dogmatic thought.
As Tyson continues the story of light through Newton's discovery of the spectrum, to William Herschel's discovery of infrared radiation, to Joseph von Fraunhofer's optics and the discovery of chemical spectroscopy, we see again why science is not just another worldview, not just one opinion floating among equals, but a vital window into the world that we don't merely inhabit, but that constitutes our very nature.
When Tyson chokes up over the retelling of discoveries which laid the foundation for his own life's work in astrophysics, we are reminded (in the words of another great philosopher) that luminous beings are we, indeed.