Two faces of physics: Kepler, harmony of the world. Rabi, the modern age.--Three faces of biology: Lysenko, enemies of the people. A sorrow and a pity, Rosalind Franklin and The double helix. Lewis Thomas, life of a biology watcher.--Fact and fantasy: Extrapolators, Arthur C. Clarke. Calculators, self-replications. Innovators, Godel's theorem