Antony van Leeuwenhoek (1632-1723) of Delft, The Netherlands, advanced the science of microscopy sometime before 1668 with his observations through a simple glass bead. Although Leeuwenhoek did not invent the microscope—compound microscopes had been in use nearly 40 years before he was born—his relatively crude, hand-built creations were an order of magnitude better than the best microscopes available at the time. Leeuwenhoek was able to describe microscopic objects, such as blood platelets and "animacules," that had never been resolved using multi-lensed instruments, and he achieved magnifications of over 200 using a single, simple lens.
by James A. Mahaffey