The existence of a prime mover- nothing can move itself; there must be a first mover. The first mover is called God.
Thomas AquinasNothing created has ever been able to fill the heart of man. God alone can fill it infinitely.
Thomas AquinasFriendship is the source of the greatest pleasures, and without friends even the most agreeable pursuits become tedious.
Thomas AquinasGood and evil are essential differences of the act of the will. For good and evil pertain essentially to the will; just as truth and falsehood pertain to the reason, the act of which is distinguished essentially by the difference of truth and falsehood (according as we say that an opinion is true or false.) Consequently, good and evil volition are acts differing in species.
Thomas Aquinas