"Encyclopedia Britannica, 11th Edition, Volume 11, Section 5" is one of the most authoritative sources of information in the world, which includes a wide range of knowledge in various fields of knowledge. This edition presents an article about Pierre Gassendy, an outstanding French philosopher, scientist and mathematician of the Enlightenment period. This article reveals the life and activities of Gassendi, his contribution to the development of philosophy and science. Additionally, this volume also features an article on the term "Geocentric System," which explains the concept that the Earth is the center of the universe and the planets revolve around it. This concept was popular before Copernicus' discovery of the heliocentric system. "Encyclopedia Britannica, 11th Edition" is an indispensable resource for all who seek to expand their knowledge in various fields of science, culture and history.