Thomas Aquinas, Compendium of Theology

Many other defects began to appear in man. Inordinate stirrings of passion quickly followed one another in the lower appetites, and at the same time the light of wisdom, which supernaturally illuminated man as long as his will was submissive to God, grew dim in his intellect. The result of this was that man turned his love to sensible objects. Immersed in these, he wandered far from God and fell into repeated sins.

Furthermore, he gave his allegiance to unclean spirits who he thought would help him to live a life of sensual pleasure and to acquire material goods. Through this process, idolatry and various kinds of sins arose in the human race. The more man yielded to their baneful influence, the farther he left behind him the knowledge and desire of spiritual and divine goods.