Aristotle (384-322 B.C.) was a Greek philosopher. He studied under Plato and wrote numerous treatises. His political beliefs were much less socialist than those of Plato. He taught Alexander the Great, who sent him back scientific reports and specimens from his campaigns.
Scholars in the Islamic Caliphate studied Aristotle in great detail, producing many commentaries which tried to reconcile his teachings with those of the Quran. Several Christian scholars smuggled translations of Aristotle's texts into Europe by studying at Islamic universities in disguise. (Later, better texts arrived with scholars fleeing the Fall of Constantinople.) Many prominent theologians, including St. Thomas Aquinas, developed the Scholastic system to reconcile Aristotle with the Bible.