His name was Antonie van Leeuwenhoek, and he lived from 1632 to 1723. Drawings from a Leeuwenhoek letter in 1683 illustrating human mouth bacteria. It is important to remember that microbes such as bacteria and viruses do far more than cause disease, and many are vital to life. Scientists’ understanding of microbes has progressed a long way since Leeuwenhoek, including the development of antibiotics against bacteria and vaccines against viruses including SARS-CoV-2. But it was Leeuwenhoek who first opened people’s eyes to life’s vast microscopic realm, a discovery that continues to transform the world.