In 1665 Robert Hooke an English scientist, observed a honeycomb structure (dead cells) with a piece of cork using a primitive compound microscope and commented that they resembled compartments in which monks lived and termed them ‘cells’. It was actually in 1838 when a German botanist Schleiden came to the conclusion that plants and animal cells were composed of cells. This was done by a using light microscope to examine cells from both plants and animals. Furthermore, Schleidon published his findings in a book and Schwann a German zoologist extended this theory to his own field. As a result both scientists concluded that all living things were composed of cells by noting this similarity from close examination of both organisms, which is one of the 3 fundamental aspects of the Cell Theory.