Romans 4:22

For that investigation, which accords with faith, which builds, on the foundation of faith, the august knowledge of the truth, we know to be the best. Now we know that neither things which are clear are made subjects of investigation, such as if it is day, while it is day; nor things unknown, and never destined to become clear, as whether the stars are even or odd in number; nor things convertible; and those are so which can be said equally by those who take the opposite side, as if what is in the womb is a living creature or not. A fourth mode is, when, from either side of those, there is advanced an unanswerable and irrefragable argument. If, then, the ground of inquiry, according to all of these modes, is removed, faith is established. …

Accordingly it is patience which is both subsequent and antecedent to faith. In short, Abraham believed God, and was accredited by Him with righteousness; but it was patience which proved his faith, when he was bidden to immolate his son, with a view to (I would not say the temptation, but) the typical attestation of his faith. But God knew whom He had accredited with righteousness. So heavy a precept, the perfect execution whereof was not even pleasing to the Lord, he patiently both heard, and (if God had willed) would have fulfilled. …

This, then, was the meaning of his safe guidance on the way to what he sought, that he was not blindly led by any of the means ready to hand for his instruction in the things of God, and that his mind, unimpeded by any object of sense, was never hindered from its journeying in quest of what lies beyond all that is known, but having gone by reasoning far beyond the wisdom of his countrymen, (I mean the philosophy of the Chaldees, limited as it was to the things which do appear) and soaring above the things which are cognizable by sense, from the beauty of the objects of contemplation, and the harmony of the heavenly wonders, he desired to behold the archetype of all beauty. …