How did St. Augustine’s philosophy influence medieval thinkers such as Anselm of Canterbury and Thomas Aquinas?

St. Augustine’s philosophy profoundly shaped medieval thought by establishing a framework that sought to harmonize faith and reason, a tradition that influenced thinkers like Anselm of Canterbury and Thomas Aquinas.12

St. Anselm of Canterbury

Anselm followed the Augustinian tradition of using both faith and reason in the search for truth, maintaining that faith must precede understanding. Like Augustine, Anselm utilized Neoplatonic thought to develop rational proofs for the existence of God. His famous ontological argument, which posits that God is the being than which none greater can be conceived, reflects this commitment to using reason to provide grounds for what is believed through faith.34

St. Thomas Aquinas

Aquinas also operated within the Augustinian tradition of viewing philosophy as an ally to religion. However, he significantly evolved this approach by integrating Aristotelian methods. While Augustinian "illuminationism"—the idea that God must illumine the human mind for knowledge to be possible—dominated the Middle Ages until the 13th century, Aquinas developed an alternative. He championed the autonomy of reason within the sphere of faith, arguing that nature has its own rational structure that leads to God. Despite his Aristotelian focus, Aquinas remained deeply influenced by the Augustinian emphasis on the necessity of grace for a nature affected by sin.156