“The gist of Augustine’s view of faith and reason is summed up in his use of the scriptural passage “Unless you believe, you shall not understand.” He takes this to indicate a temporal priority of faith to understanding—as if to say, faith is where we begin but understanding is where we end up. And of course it is the end, the goal or telos, which gives meaning to the beginning—for as Augustine insists very emphatically, the journey is pointless apart form its destination. In one of his latest writings, Augustine says, “It is begun in faith, but completed by sight,” echoing one of his earliest works, in which he says, “Authority comes first in time, but Reason is first in reality. […] The road to understanding often begins with our believing what our teachers tell us—as when we believe a mathematical formula on the authority of our math teacher, even though we cannot really see what it means. But of course if we are good students then we desire to understand the changeless truth it signifies—to see it for ourselves, with our own mind’s eye.”
–Philip Cary, Augustine’s Invention of the Inner Self (Oxford University Press, 2000), p. 145.
Cf. Anselm: “I do not seek to understand so that I may believe; but I believe so that I may understand.”