Greek philosopher, scientist, and physician. His encyclopedic writings cover nearly all fields of knowledge: logic, metaphysics, ethics, rhetoric, poetry, biology, zoology, physics, and psychology.

For Aristotle, matter consisted of earth, water, air, and fire. In this sense, he can be considered the true founder of the "humus theory," which persisted for nearly 2000 years. This theory posits, in simplified terms, that the carbon contained in plants originates from humus—decayed organic matter.