Unremitting and fierce is the devil in his attacks on us, and on all sides he lies in wait against our salvation. We must therefore be very vigilant, and cut off from every side his approach to us. For if he find but the least opening, he will soon make for himself a broad way, and then gradually enter in with all his forces. If we have any real care for our salvation, let him not come near us, even in small matters, so that we may be free to meet him more vigorously in greater things. For it would be very grievous foolishness indeed, that while he employs such zeal to destroy our soul, we show no equal anxiety for its salvation.

Not without reason do I say this to you, because I fear lest that wolf even now, unseen by us, may be standing in the midst of this sacred enclosure, and because of their own folly, and his guile, may have seized on one of the flock from among those now listening to me. If we could see the wounds he inflicts, or if his blows were felt by the body, it would not be difficult to guard against his plotting. But because the soul is invisible, and the wounds it receives are invisible, we have need of the greatest watchfulness, so that every man may prove himself. For: what man knoweth the things of a man, but the spirit of a man that is in him? (1 Cor. 2:11)