Many people, envisaging the future of this planet, see a dark, dysfunctional world in which humans have destroyed the environment and superheated the climate. Others regard technology, along with the constant ability of humans to innovate, as a panacea that will cure every ill. It seems our future will resemble either Blade Runner or Star Trek. But why is there such a divergence in our perceptions of the future and our role in shaping it? Charles Mann, in his beautifully written The Wizard and the Prophet, shows us how in the 20th century these radically different views were personified by two charismatic American scientists, William Vogt and Norman Borlaug.