Alexander von Humboldt (1769 1859) was an intellectual giant: an explorer who helped lay the foundations of biogeography, a naturalist who influenced Charles Darwin, and a botanist who developed a model of the Earth's climate zones. He travelled extensively in Europe, carried out scientific explorations across the Russian Empire and in Latin America, and devoted much energy to seeking a unified view of the different branches of scientific knowledge. Ansichten der Natur, published in 1808 with a second edition in 1826, aimed to 'engage the imagination' as well as to communicate new ideas, and...