Carl sagan speaks zeitgeist. Humility - Carl Sagan. THE SAGAN SERIES (part 1) - The Frontier Is Everywhere. Carl Sagan On Evolution. Carl Sagan on the Big Bang / the creation of the cosmos. A Universe Not Made For Us [Carl Sagan Tribute Series, S01E01] Carl Sagan "100 Billion Galaxies each W/100 Billion Stars"