This challenging and innovative book examines the processes involved in the birth and development of new scientific ideas. The author has searched for strategies used by scientists for producing new theories, both those that yield a range of plausible hypotheses and ones that aid in narrowing that range. She goes on to focus on the development of the theory of the gene as a case study in scientific creativity. Her discussion of modern genetics greatly demystifies the philosophy of science, and establishes a realistic framework for understanding how scientists actually go about their work.