The Renaissance period, beginning in the late fourteenth century, ended the scientific and intellectual stagnation of the Dark Ages and sparked a new period of discovery. In this period, often called the Age of Discovery, several inventions came about that greatly affected the world. Included among these inventions was the microscope, a scientific innovation that greatly affected the history of water filters.
Long before the actual use of a microscope as we know it today, people had recognized the power of concave glass to make items appear larger and to focus heat from the sun. This discovery was little used until the advent of spectacles in the mid-thirteenth century. It wasn't until the late sixteenth century that such concave pieces of glass, or “lenses” as they were called, became relevant to the history of microscopy, and, consequently, to the history of water filters. In 1590, two Dutch spectacle makers, Zaccharias Janssen and his son Hans, began experimenting with lenses in a tube and found that they could greatly magnify objects viewed through the tube (Wilson, 1995). This invention was the forerunner to modern-day telescopes and microscopes.
A century later, Anton van Leeuwenhoek, considered the father of microscopy, built upon the Janssen’s simple invention. By grinding and polishing the tiny curved lenses, he was able to reach magnifications of up to 270 times the original object (Wilson, 1995). This advanced microscope had a great effect upon the study of water purity and water filtration. Scientists were now able to view tiny material particles present in water that had been presumed to be clean.