The cell was discovered in 1665 by Robert Hooke when he examined thin slices of a cork with a microscope. What he saw were not living cells but nonliving cell walls. Hooke reportedly used the word "cells" for what he saw, because the cork reminded him of monastery cells.
In 1674, Antonie van Leeuwenhoek was the first person to see bacteria, yeast and the various organisms found in only a small drop of water by using a microscope. Leeuwenhoek is often referred to as the father of microscopy. The discoveries made by Hooke and Leeuwenhoek changed scientific theory from vitalism to cell theory.