115. There are some men who maintain from firm conviction that without the Word a man can know of the existence of God, of heaven and hell, and also something of the other matters taught in the Word. They thereby weaken the authority and the holiness of the Word, if not with the mouth yet in the heart. Therefore, one may not argue with them from the Word, but from the light (lumen) of natural reason; for they do not believe in the Word but in themselves. Inquire then, by the light of reason, and you will find that there are two faculties of life in man, called the understanding and the will; and that the understanding is subject to the will, and not the will to the understanding; for the understanding merely teaches and points out the way.
Inquire further and you will find that man's will is his proprium, and this when regarded in itself is entirely evil, and in consequence of this, that falsity arises in the understanding. [2] Having learned these things, you will perceive that a man of himself does not desire to understand anything but what comes from the proprium of his will; and that there is no possibility of doing this unless there were some other source of knowledge. Man from the proprium of his own will does not desire to understand anything but what relates to himself and the world; anything beyond this is in thick darkness to him. For instance, if, when looking at the sun, moon and stars, he should reflect on their origin, he could not but think that they are self-originated. He could not think any more profoundly that many of the learned men in the world who, although they know from the Word that God created all things, yet acknowledge nature [as creator]. Still more would they do so had they known nothing from the Word. Is it credible that Aristotle, Cicero, Seneca and other ancient sages who have written about God and the immortality of the soul first derived their knowledge from their proprium? No; they obtained it by tradition from others who first learned it from the [Ancient] Word. Nor do writers on natural religion derive their knowledge from themselves; they only confirm by rational deduction what they learn from the Church which has the Word; and it is possible that some of those who confirm truths do not believe them.