Why did Aquinas believe that revelation supplements rather than replaces reason?

Thomas Aquinas maintained that revelation supplements rather than replaces reason because he viewed faith and reason as distinct but compatible paths to truth, both rooted in the order of creation.12

In his Thomist framework, Aquinas argued that human reason, operating through its own natural laws, is capable of establishing certain truths, such as the existence of God and the immortality of the soul. However, he recognized that not all individuals have the capacity or opportunity for such strenuous intellectual activity. Revelation serves to make these essential truths accessible to all believers.13

Furthermore, Aquinas held that revelation extends beyond the limits of natural reason to disclose mysteries—such as the triune nature of God and the divinity of Christ—that cannot be discovered by philosophy alone. By integrating these domains, Aquinas affirmed the dignity of reason, arguing that grace does not destroy nature but rather perfects and elevates it. Thus, for Aquinas, the two are fundamentally consistent, as both originate from the same divine source.124