An Italian theologian, the foremost Christian philosopher of the Middle Ages, and often called the greatest Roman Catholic theologian. He was educated at Naples, became a Dominican in 1243, and studied theololgy at Cologne and at Paris under Albertus Magnus. He taught at Paris, then returned to Italy and lectured at the papal court, 1259-68. He then returned to Paris to dispute the interpretation of Aristotle. St. Thomas Aquinas was the greatest of the scholastics.
Scholasticism is an attempt to rationalize in order to buttress faith by reason.
St. Thomas also first explicitely stated the doctrine of causality, that nothing can exist without a cause and therefore the Sacraments are true causes of grace and not mere by-products of grace. St. Thomas rejected the theory of the Immaculate Conception of Mary, claiming that this would destroy the universality of Christ's salvation. From READ ME OR RUE IT by Fr. 11 N. Whitehall Rd. St. Thomas, the Prince of theologians, says that the fire of Purgatory is equal in intensity to the fire of Hell.