St. Augustine about faith and reason

“I understand, and I also believe everything I understand, but not everything I believe, I understand.”

St. Augustine's De Magistro, chapter XI

A symbiosis between reason and faith, in such a way that they mutually 

in the sense that one leads to the other, from which it is necessary to believe in order to understand and to understand in order to believe, in other words, to believe so that faith can help the intellect to understand, and to understand so that the intellect can find faith.