Luke 22:55

And by this time there was a fire burning in the house of the High Priest; as it follows, And when they had kindled a fire, &c. Peter came to warm himself, because his Lord being taken prisoner, the heart of his soul had been chilled in him.

(App. Serm. 79.) For to Peter were delivered the keys of the kingdom of heaven, to him were entrusted an innumerable multitude of people, who were wrapped up in sin. But Peter was somewhat too vehement, as the cutting off the car of the High Priest's servant betokens. If he then who was so stern and so severe had obtained the gift of not sinning, what pardon would he have given to the people committed to him? Therefore Divine Providence suffers him first to be holden of sin, that by the consciousness of his own fall he might soften his too harsh judgment towards sinners. When he wished to warm himself at the fire, a maid came to him, of whom it follows, But a certain maid beheld him, &c.

And when they kindled a fire in the midst of the courtyard and sat around it, Peter was in their midst. There is a fire of love, and there is also a fire of desire. Of this, it is said: "I came to cast fire on the earth, and what will I, if it be already kindled?" (Luke 12:49). Of that: "Behold, all you that kindle a fire, that gird yourselves with flames: walk in the light of your fire, and in the flames that you have kindled" (Isaiah 50:11). This fire, descending from heaven upon the believers in the upper room of Zion, taught them to praise God in various tongues. That fire, kindled from earthly materials of Caiaphas in the courtyard, inflamed the crowds to deny the Lord. With this fire, Moses burned the head of the golden idol, with that Zedekiah burned the writings of Jeremiah prophesying. Whoever extinguishes a vicious and harmful fire within himself can sing to the Lord: "For I am become like a bottle in the frost, I have not forgotten your statutes" (Psalm 119:83). But he who loses the flame of virtues hears from the Lord: "Because iniquity has abounded, the charity of many will grow cold" (Matthew 24:12). Numbed by this chill for a moment, Apostle Peter desired to be warmed by the coals of the persecutors, because he sought the temporary comfort of their company. But without delay, being regarded by the Lord, he abandoned both their physical fire and the infidelity in his heart.