Miscellanies 2.11.49

For example, he says: “If you have faith like a grain of mustard seed, you will move the mountain”; and again: “According to your faith let it be done to you.” And one is healed, receiving healing by faith, and another who is dead is raised through the strength of the one who believed that he would be raised. But demonstration based on opinion is human, and comes from rhetorical arguments or even dialectical syllogisms. For the highest demonstration, which we have hinted is scientific, implants faith, through the setting forth and opening up of the Scriptures, in the souls of those who long to learn; and this would be knowledge. For if what is taken up for the question is accepted as true, being divine and prophetic, it is clear that the conclusion drawn from them will also consequently be true; and knowledge would rightly be for us a demonstration.