A haughty person is not aware of his faults, or a humble person of his good qualities. An evil ignorance blinds the first, an ignorance pleasing to God blinds the second.
The evil one cannot comprehend the joy we receive from the spiritual life; for this reason he is jealous of us, he envies us and sets traps for us, and we become grieved and fall. We must struggle, because without struggles we do not obtain virtues.