Explains how life is sustained on Earth through the presence of water, food, and oxygen, and how the planet is different from a spacecraft because it can rejuvenate its supply of these critical resources.
Describes the 1994 discovery made in Chauvet, France, of a cave with Stone Age rock paintings, and discusses the significance of cave art to people living in prehistoric as well as modern times.
Explains various changes in humanity's beliefs about the shape of the earth, from the flat earth theories of the ancients to the round earth theories which were proven true by the voyages of Columbus and Magellan.