Although five years had passed since Lister presented his case to the Medical Congress at the Centennial Exhibition, many American doctors still dismissed not just his discovery, but even Louis Pasteur’s. They found the notion of “invisible germs” to be ridiculous, and they refused to even consider the idea that they could be the cause of so much disease and death. “In order to successfully practice Mr. Lister’s Antiseptic Method,” one doctor scoffed, “it is necessary that we should believe, or act as if we believed, the atmosphere to be loaded with germs.”