In this classic international bestseller, first published in 1926, bacteriologist and pathologist Paul de Kruif offers an accessible and fascinating account of the first scientists to explore the microscopic world. Included are the “father of microbiology,” Antonie van Leeuwenhoek, who created lenses to study the microscopic world, and Louis Pasteur, whose discovery of a vaccine for rabies would save many lives. The legacy of the thirteen researchers and scientists profiled by de Kruif continues today, influencing research in the current fight against viruses such as SARS-CoV and HIV/AIDS. 
Paul de Kruif (1890–1971) was a bacteriologist and pathologist who wrote widely about medical science. He taught at the University of Michigan, Ann Arbor, and worked as a researcher for the Rockefeller Institute (now The Rockefeller University) in New York City.