1 Samuel 10:9

So then, when He turned His shoulder, etc. When the Lord went away from John, immediately obeying the command of paternal dispensation, He was changed in a new thought, so that He who hitherto had been subject to His parents and was considered like other mortals, from then on, by the clear proofs of virtues, would also be revealed as God. And all that John had spoken of Him, and what other prophets had predicted, were true.

23. For the heart is changed to another when it is directed toward desiring better things; the heart is also changed when it is abandoned to evil. But in the case of Saul, who was first good and afterward evil, how this ought rather to be understood literally is not very clear. But if it is said with reference to his advancement, he had a changed heart, because he who had been searching for donkeys was now thinking about the governance of a kingdom. If, however, he is understood to have then received an evil heart, he was humble before the prophet; but as he began to depart, he likewise began also to grow proud. In his mind he was already thinking of himself not as a little one but as a king. He was not yet exalted in rank, but he was exalted in his own estimation. But since throughout this sacred history nothing is yet openly said about his pride, we too act more rightly if for the time being we pass over in silence what might seem unfavorable about him. What can still support his remaining innocence is said in what follows: That Saul was a child of one year when he began to reign, and he reigned two years over Israel (1 Sam. 13:1). For if he was a humble king for two years, the changed heart is asserted of him on account of the vigor of his purpose, not on account of a new swelling of pride. Therefore, in that Saul is said to have had a changed heart, he is likened to new preachers of the holy Church, who when they receive the office of preaching become better through divine grace. For Samuel anointed Saul as prince, but God changed his heart to another, because we receive the sacraments of holy orders outwardly from the teachers of the Church, but we are strengthened inwardly by the power of the sacraments from Almighty God. The power of the sacrament, however, is the grace of the sevenfold Spirit. Those who receive this grace are surely changed as if having received another heart, because those whom the Holy Spirit strengthens by his grace, he immediately makes to be what they were not. So indeed the disciples of the Redeemer also formerly were afraid; but when through the coming of the Holy Spirit another heart was changed in them, they preached the word of God with boldness (Acts 4:31). For God changed their heart to another, to whom he granted knowledge of all languages (Acts 2:6). For he changed their heart to another whom he clothed with wondrous…