“It almost always happens that interior sentiments of pride precede the commission of grievous sins. Peter was not aware of his own weakness. He preferred himself before others; he trusted in himself as though he were incapable of sinning, boasting that no temptation would separate him from Jesus. He would not even believe the assurance of his Divine Master, that he would deny him thrice. Deceived by this vain confidence in his own strength, he neglects to pray, and to have recourse to God; and God, in His justice, permits him to fall, in punishment of his pride. There is nothing more dangerous than to confide in our own strength, and trust to feelings of fervor. We are full of malice, and capable of committing the most enormous crimes, unless God supports us.”
— Fr. Ignatius of the Side of Jesus, p. 85-6