The obstacles to discovery - the illusions of knowledge - are also part of the story. In this work, Boorstin captures the illusions about the past - the earth before Columbus and Balboa, Magellan and Captain Cook, about the heavens before Copernicus and Galileo, about the human body before Paracelsus and Harvey, plants before Linnaeus, the past before Petrarch, wealth before Adam Smith, the physical world before Newton, Dalton, Faraday and Einstein. He asks unfamiliar questions: why didn't the Chinese discover Europe or America? Why did people take so long to learn that the earth goes around the sun?