The Conferences Of John Cassian by John Cassian
Chapter VIII. How it is more wonderful to have cast out one's faults from one's self than devils from another.
And in truth it is a greater miracle to root out from one's own flesh the incentives to wantonness than to cast out unclean spirits from the bodies of others, and it is a grander sign to restrain the fierce passions of anger by the virtue of patience than to command the powers of the air, and it is a greater thing to have shut out the devouring pangs of gloominess from one's own heart than to have expelled the sickness of another and the fever of his body. Finally it is in many ways a grander virtue and a more splendid achievement to cure the weaknesses' of one's own soul than those of the body of another. For just as the soul is higher than the flesh, so is its salvation of more importance, and as its nature is more precious and excellent, so is its destruction more grievous and dangerous.