In this international bestseller, bacteriologist and pathologist Paul de Kruif tells, in an accessible and engaging form, about the first scientists who explored the microscopic world. Among them are “the father of microbiology” Antonie van Leeuwenhoek, who created lenses to study the microscopic world, and Louis Pasteur, whose discovery of a rabies vaccine saved many lives. The legacy of the researchers and scientists covered in this book continues to be useful to this day, influencing research in the fight against many viruses.