In 1677, just twenty years after William Harvey's death, Dutch scientist Antonie van Leeuwenhoek created a microscope powerful enough to magnify the sperm found in semen. Because Harvey could not ...

In the 17th century, a Dutch merchant named Antony van Leeuwenhoek began experimenting with making new microscope lenses and, in the process, plunged humanity into a new world—this one teeming with ...