Aristotle (384–322 BCE), the ancient Greek philosopher, wrote extensively about animals; De Animalibus is a 19-volume collection of three of his works: Historia Animalium, De Partibus Animalium, and De Generatione Animalium. In addition to his studies of animals, he exerted a profound influence on Western philosophy and scholarship from Antiquity through the Renaissance. A person with wide-ranging interests, he wrote about medicine, science, and other topics. Aristotle understood the four elements of earth, water, air, and fire as the building blocks of the universe, a concept later used in “four humors” theory.