“Envy weakens us spiritually. Why do you think the Apostles, having received such authority from Christ and having expelled other demons, were not able to expel the demon from the possessed child? It was because they were envious of the three disciples – Peter, James and John – whom Jesus had taken to Mount Tabor for His Transfiguration. Christ could have taken all the disciples, but not all of them had the capacity yet to receive the mystery, and so He took only the three who had greater capacity. Did you think He did not love the other disciples as well? Or that He loved John more than the others? No, but John loved Christ more than the other disciples loved Him, which is why he was better able to understand the love of Christ. He had greater capacity; he had a bigger “battery”. Do you see how envy distanced the Grace of God from the other disciples, rendering them incapable of healing the possessed child?”
– ‘Passions and Virtues’