Thomas Aquinas:

Thomas will forever be remembered as the guy who supposedly proved the existence of God by arguing that the Universe had to have been created by something, since everything in existence has a beginning and an end. This is now referred to as the “First Cause” argument, and all philosophers after Thomas have wrestled with proving or disproving the theory.

He actually based it on the notion of “ού κινούμενον κινεῖ,” of #1. The Greek means “one who moves while not moving” – or “the unmoved mover”. St. Thomas Aquinas also uniquely addressed appropriate social behavior toward God. In so doing, he gave his ideas a contemporary — and some would say timeless — everyday context. Aquinas believed that the laws of the State were, in fact, a natural product of human nature, and were crucial to social welfare.

By abiding by the social laws of the State, people could earn eternal salvation of their souls in the afterlife. St. Thomas Aquinas identified three types of laws: natural, positive and eternal. According to his treatise, natural law prompts man to act in accordance with achieving their goals. It governs man's sense of right and wrong. Positive law is the law of the State, or government, and should always be a manifestation of natural law.

He made five famous arguments for the existence of God, which are still discussed hotly on both sides: theist and atheist. Of those five, which he intended to define the nature of God, one is called “the unity of God,” which is to say that God is not divisible. He has essence and existence, and these two qualities cannot be separated. Thus, if we are able to express something as possessing two or more qualities, and cannot separate the qualities, then the statement itself proves that there is a God, and Thomas’s example is the statement, “God exists,” in which statement subject and predicate are identical.

Thomas founded everything he postulated firmly in Christianity, and for this reason, he is not universally popular, today. Even Christians consider that, since he derived all his ethical teachings from the Bible, Thomas is not independently authoritative of any of those teachings. But his job, in teaching the common people around him, was to get them to understand ethics without all the abstract philosophy. He expounded on #2′s principles of what we now call “cardinal virtues:” justice, courage, prudence and temperance. He was able to reach the masses with this simple, four-part instruction.

On his deathbed, St. Thomas Aquinas uttered his last words to the Cistercian monks who had so graciously attended him: “This is my rest forever and ever: here will I dwell for I have chosen it.” (Psalm 131:14) “The Universal Teacher” died at the monastery of Fossanova on March 7, 1274, and was later canonized by Pope John XXII in 1323.