16 Let us return to the words of the Psalm. “They shall bear You in their hands, lest at any time Thou hurt Your foot against a stone”. Christ was raised up in the hands of Angels, when He was taken up into heaven: not that, if Angels had not sustained Him, He would have fallen: but because they were attending on their King. Say not, Those who sustained Him are better than He who was sustained. Are then cattle better than men, because they sustain the weakness of men? And we ought not to speak thus either; for if the cattle withdraw their support, their riders fall. But how ought we to speak of it? For it is said even of God, “Heaven is My throne.” Because then heaven supports Him, and God sits thereon, is therefore heaven the better? Thus also in this Psalm we may understand it of the service of the Angels: it does not pertain to any infirmity in our Lord, but to the honour they pay, and to their service....What the finger of God is, the Gospel explains to us; for the finger of God is the Holy Ghost. How do we prove this? Our Lord, when answering those who accused Him of casting out devils in the name of Beelzebub, says, “If I cast out devils by the Spirit of God;” and another Evangelist, in relating the same saying, says, “If I with the finger of God cast out devils.” What therefore is in one stated clearly, is darkly expressed in another. You did not know what was the finger of God, but another Evangelist explains it by terming it the Spirit of God. The Law then written by the finger of God was given on the fiftieth day after the slaughter of the lamb, and the Holy Ghost descended on the fiftieth day after the Passion of our Lord Jesus Christ. The Lamb was slain, the Passover was celebrated, the fifty days were completed, and the Law was given. But that Law was to cause fear, not love: but that fear might be changed into love, He who was truly righteous was slain: of whom that lamb whom the Jews were slaying was the type. He arose from the dead: and from the day of our Lord's Passover, as from that of the slaying of the Paschal lamb, fifty days are counted; and the Holy Ghost descended, now in the fullness of love, not in the punishment of fear. Why have I said this? For this then our Lord arose, and was glorified, that He might send His Holy Spirit. And I said long ago that this was so, because His head is in heaven, His feet on earth. If His head is in heaven, His feet on earth; what means our Lord's feet on earth? Our Lord's saints on earth. Who are our Lord's feet? The Apostles sent throughout the whole world. Who are our Lord's feet? All the Evangelists, in whom our Lord travels over all nations....We need not therefore wonder that our Lord was raised up to heaven by the hands of Angels, that His foot might not dash against a stone: lest those who on earth toiled in His body, while they were travelling over the whole world might become guilty of the Law, He took from them fear, and filled them with love. Through fear Peter thrice denied Him, for he had not yet received the Holy Ghost: afterwards, when he had received the Holy Spirit, he began to preach with confidence....Our Lord so dealt with him, as if He said, thrice you have denied Me through fear: thrice confess Me through love. With that love and that charity He filled His disciples. Why? Because He has set His house of defence very high: because when glorified He sent the Holy Ghost, He released the faithful from the guilt of the Law, that His feet might not dash against a stone.
17. “Thou shall go upon the asp and the basilisk; the lion and the dragon shall you tread under your feet”. You know who the serpent is, and how the Church treads upon him, as she is not conquered, because she is on her guard against his cunning. And after what manner he is a lion and a dragon, I believe you know also, beloved. The lion openly rages, the dragon lies secretly in covert: the devil has each of these forces and powers. When the Martyrs were being slain, it was the raging lion: when heretics are plotting, it is the dragon creeping beneath us. You have conquered the lion; conquer also the dragon: the lion has not crushed you, let not the dragon deceive you....A few women in the Church have bodily virginity: but the virginity of the heart all the faithful have. In the very matter of faith he feared that the heart's virginity would be corrupted by the devil: and those who have lost it, are uselessly virgins in their bodies. What does a woman who is corrupt in heart preserve in her body? Thus a Catholic married woman is before a virgin heretic. For the first is not indeed a virgin in her body, but the second has become married in her heart; and married not unto God as her husband, but unto the dragon. But what shall the Church do? The basilisk is the king of serpents, as the devil is the king of wicked spirits.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)