. . . . . my work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof. Antony van Leeuwenhoek. Letter of June 12, 1716

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.