Book Review of Nature’s Chemicals. Richard Firn. 2009. Oxford University Press, New York. Pp. 264. $44.95 (paper). ISBN9780199603022.

Nature's Chemicals, by plant biologist Richard Firn, is introduced by the author as "a book about ideas." This opening is unexpected because based on the book's subtitle, The Natural Products that Shaped our World, one would think it would be the typical layman's history of economically relevant plant compounds such as coffee, rubber, and quinine a la National Geographic. Instead, as promised, the reader is introduced to ideas concerning not just natural products—the economics, biochemistry, and evolution thereof—but ideas about the nature of science itself. The most famous idea detailed in the book is the "Screening Hypothesis," which Firn developed in 1991 in conjunction with his former graduate student, Clive Jones. As he explains in Chapter 5, the Screening Hypothesis states that to maintain and improve the biodiversity of the world's Natural Products, a certain amount of diversity and flexibility must be present in the biochemical processes that create them. This implies some radical thinking.