Antony van Leeuwenhoek was an unlikely scientist. A tradesman of Delft, Holland, he came from a family of tradesmen, had no fortune, received no higher education or university degrees, and knew no languages other than his native Dutch. This would have been enough to exclude him from the scientific community of his time completely. Yet with skill, diligence, an endless curiosity, and an open mind free of the scientific dogma of his day, Leeuwenhoek succeeded in making some of the most important discoveries in the history of biology. It was he who discovered bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells, microscopic nematodes and rotifers, and much more. His researches, which were widely circulated, opened up an entire world of microscopic life to the awareness of scientists.
Leeuwenhoek was born in Delft on October 24, 1632. (His last name, incidentally, often is quite troublesome to non-Dutch speakers: "layu-wen-hook" is a passable English approximation.) His father was a basket-maker, while his mother's family were brewers. Antony was educated as a child in a school in the town of Warmond, then lived with his uncle at Benthuizen; in 1648 he was apprenticed in a linen-draper's shop. Around 1654 he returned to Delft, where he spent the rest of his life. He set himself up in business as a draper (a fabric merchant); he is also known to have worked as a surveyor, a wine assayer, and as a minor city official. In 1676 he served as the trustee of the estate of the deceased and bankrupt Jan Vermeer, the famous painter, who had had been born in the same year as Leeuwenhoek and is thought to have been a friend of his. And at some time before 1668, Antony van Leeuwenhoek learned to grind lenses, made simple microscopes, and began observing with them. He seems to have been inspired to take up microscopy by having seen a copy of Robert Hooke's illustrated book Micrographia, which depicted Hooke's own observations with the microscope and was very popular.
Leeuwenhoek is known to have made over 500 "microscopes," of which fewer than ten have survived to the present day. In basic design, probably all of Leeuwenhoek's instruments -- certainly all the ones that are known -- were simply powerful magnifying glasses, not compound microscopes of the type used today. A drawing of one of Leeuwenhoek's "microscopes" is shown at the left. Compared to modern microscopes, it is an extremely simple device, using only one lens, mounted in a tiny hole in the brass plate that makes up the body of the instrument. The specimen was mounted on the sharp point that sticks up in front of the lens, and its position and focus could be adjusted by turning the two screws. The entire instrument was only 3-4 inches long, and had to be held up close to the eye; it required good lighting and great patience to use.