John Chrysostom: General Revelation in Creation and Conscience

So one way to knowledge of God is through the whole of creation; another, not inferior, is the way of conscience, which we on that occasion developed at great length, showing how the knowledge of things that are good and things that are not is acquired by us automatically, and how conscience inspires us with this interiorly. These two, in fact, have been our teachers from the beginning -- creation and conscience: without either of them uttering a word, they taught human beings in silence, creation making an impression on the observer through vision and leading the observer of everything to the marvel of its maker, conscience inspiring us within and suggesting all that has to be done, so that through the visible aspect we grasp his power and the verdict he delivers. That is to say, whenever it accuses sin on the inside, it suffuses the countenance outside, and fills us with deep regret. Again, it renders us pale and timid when we are caught in something shameful; and while we do not hear a word, we perceive the irritation happening within from the external aspect.

- John Chrysostom (around A.D. 347 to around A.D. 407), Homilies on Hannah, Homily 1, in St. John Chrysostom, Old Testament Homilies, Volume 1, pp. 70-71 (2003), Robert C. Hill translator.