# Aristotelian belonging to or having some relation to Aristotle (384-322 B.C.), Greek philosopher noted for his works on logic, ethics, politics, etc. Aristotle's book Ethics contains the doctrine that virtue consists in a mean between excess and deficiency. He disagreed with his teacher, Plato (427-347 B.C.) over the existence of ideal forms or ideas, such as truth or good. Plato held that these exist in a realm beyond the material world, while Aristotle believed that form and matter are always joined. See also Aristotle in this glossary.