Thou seest that everywhere the Scripture calleth sins “thorns.” For David also saith, “I was turned into mourning when a thorn was fixed in me.” ( Ps. xxxii. 4 , so LXX.) For it does not simply come on us, but is fixed in; and even if but a little of it remain in, even if we take it not out entirely, that little of itself in like manner causes pain, as in the case of a thorn. And why do I say, ‘that little of itself’? Even after it has been taken out, it leaves therein for a long time the pain of the wound. And much care and treatment is necessary, that we may be perfectly freed from it. For it is not enough merely to take away the sin, it is necessary also to heal the wounded place.