Bill Nye narrates the story of how photosynthesis was discovered. He explains the hypothesis of the experiment that shed light on how plants generate energy.

Ed Walters speaks with Albert Einstein and mentions his theory of relativity. Einstein humbly says he too is still figuring out how his theories work.

Hank provides background information on the biologist who contributed to evolutionary history: Charles Darwin. He also explains the four principles of Darwin's idea of natural selection, which are variation, heritability, struggle for existence, and survival and reproduction rates. Key Words: Genetic Drift, Fitness, Variations of Phenotype, Heritable, The Struggle for Existence, Survival and Reproduction Rates

A short biography of Albert Einstein, German-born scientist who revolutionized the understanding of physics and the philosophy of science. This "Man of the Century" developed the theory of relativity and impacted the development of everything from lasers to cell phones.

Charles Darwin struggles with the meaning of his research, and Thomas Huxley tells him that his theory of evolution has "killed God" because it offers a scientific explanation for the species of the world. Darwin realizes that his research will be used as ammunition in favor of science over religion.