In the 1670s the Dutch cloth merchant Antonie van Leeuwenhoek ground tiny glass lenses and looked at pond water, scrapings from teeth and rainwater. He saw living "animalcules" that nobody had known existed. His single-lens microscopes magnified up to roughly 270 times. A modern school microscope can magnify 1,000 times, but there is a catch: bigger magnification is not the same as a clearer picture.