"Cosmos" and Sagan did not disappoint viewers' desires for a serious discussion of science and astronomy from a person so qualified to offer one. Indeed, a fair criticism of "Cosmos" is that the scientific material presented—the theory of relativity, the lives of the stars, the conjecture of a fourth dimension—was too difficult for television discussion. Nonetheless, Sagan's skill as a teacher, as someone able to make the complex understandable, was always evident. It is doubtful that viewers could learn more about science in 13 hours than they did from "Cosmos." This is the triumph of the series, and Sagan's performance is far superior to the travelogue narrations of many science-nature shows….

While "Cosmos" succeeds where other programs have failed or bored, Sagan's own ambitions exceed those of the conventional teacher of science, the conveyor of facts and method. Sagan seeks to make science not only understandable, but...