While he wasn't a trained scientist, he was a Dutch draper and lens grinder who had a remarkable talent for crafting microscopes. He used his microscopes to examine a wide variety of specimens, including pond water, rainwater, and his own saliva. It was in these samples that he observed tiny, moving creatures, which he called "animalcules."
These "animalcules" were actually bacteria, and Leeuwenhoek's observations were groundbreaking, as they revealed a whole new world of microscopic life that was previously unknown.
