On the passage, "The angel of the Lord appeared to him, standing at the right side of the altar of incense."
OF THEMSELVES, beings that are corporeal and lack sensation do nothing to be seen by another. The observer's eye is simply directed toward them. Whenever the observer directs his gaze and his regard at them, he sees them, whether the objects will it or not. What can a man or any other object that is enclosed in a solid body do to avoid being seen, when they are in fact there? In contrast, things that are from above and divine are not seen, even when they are there, unless they themselves will it. It lies within their will to be seen or not. It was by an act of his grace that God appeared to Abraham and the other prophets. The eye of Abraham's heart was not the only cause that allowed him to see God; God offered his grace to the sight of a just man to let him see.
2. You should understand this not only of God the Father, but also of our Lord and Savior and of the Holy Spirit and-- to come to lesser beings--of cherubim and seraphim. Perhaps an angel is helping us as we are speaking now, but we cannot see him because we do not deserve to. Even though the eye of our body or our soul makes an effort to see, the man who wants to see will not, unless the angel willingly appears and offers himself to sight. Thus, wherever Scripture says, "God appeared" to someone--just as here, for example, "The angel of the Lord appeared to him, standing at the right side of the altar of incense"1.--understand it as I explained. Whether it is____________________