I saw Satan as lightning, &c. Many expound it in this manner: I, who am from eternity, saw Satan with all the rebellious angels, as glorious as they were, fall from heaven; fear then, and tremble, though you have received such favours from God. Others take it in this sense, that Christ, by his incarnation, hath seen the power of the devils lessened and confounded, according to what he also said, (John xii. 31.) Now shall the prince of this world be cast out. (Witham)

What connexion have these words with what goes before? Some understand them thus: the reign of the devil is near at an end; this prince of darkness is going to be overturned; he will fall from the air, where he reigns, with the same precipitation as lightning, which cuts the clouds and presently disappears. It is almost the same thing he says in other places. “The prince of this world is already judged; behold now is the judgment of this world; behold now the prince of this world shall be cast forth! When I sent you to preach the gospel to the poor, I saw Satan fall; I saw his empire overturned. The last effort which this empire of darkness shall make is the death of our Saviour, as he himself says: This is your hour, and the power of darkness. Since his resurrection he has bound the dragon in the abyss for a thousand years; he has shut up the entrance, and sealed it with his seal.” (Apocalypse xii. 9. and xx. 2.) Others think that Jesus speaks here of the fall of Lucifer, at the beginning of the creation. Wishing to give his disciples a lesson in humility, on account of the vain complacency which he saw they took in the miracles they wrought, he says to them: Beware of pride, that precipitated the first angel from heaven: I have seen him in the glory with which he was surrounded, and I have seen him hurried into the abyss. Fear, lest the same should happen to you. The former explanation appears to us more simple and literal. (Calmet)