In so doing, Sagan also explains how the scientific method is used to advance humanity's knowledge, and why science is the best way to understand the world around us. Sagan presents science as a body of knowledge, a way of thinking and an attempt to understand the world. He explains how scientists must be both extremely imaginative and extremely skeptical, that scientific discovery always contains some uncertainty, and that even scientific mistakes can help advance knowledge. He is also careful to stress that science is far from a perfect instrument – citing multiple failures of his own - it’s just the best tool available.
Sagan jumps right in with both feet in Chapter 1 (The Most Precious Thing), recounting a story of the cab driver "William F. Buckley” he once met. "Buckley" is interested in things like the lost continent of Atlantis, UFO abductions, Nostradamus and other propositions. Sagan gently and patiently explains to him time after time that there is no evidence to back up any of his theories. As it finally sinks in, “Buckley’s” face droops lower and lower, sadly