Aristotle was a Greek philosopher and polymath. He was born in the city of Stagira in Northern Greece during the Classical period. At the age of 18 he joined Plato's Academy in Athens and remained there for 20 years. He made contributions to all fields of philosophy and science. Aristotle proposed that there were three principles used in making an argument: ethos, pathos and logos. He was Alexander the Great’s mentor and taught him and his friends about medicine, philosophy, morals, religion, logic, and art. One of his famous quotes is that: “It is impossible to be really good without wisdom or to be really wise without moral virtue”.