Prov 20:30

“The sick are to be admonished to consider how great a boon is bodily affliction, which both washes away committed sins and restrains those which might have been committed, which inflicts on the troubled mind wounds of penitence derived from outward stripes. Whence it is written, "The blueness of a wound cleanseth away evil, and stripes in the secret parts of the belly." For the blueness of a wound cleanseth away evil, because the pain of scourges cleanses iniquities, whether meditated or perpetrated. But by the appellation of belly the mind is wont to be understood. For that the mind is called the belly is taught by that sentence in which it is written, "The spirit of man is the lamp of the Lord, which searcheth all the secret parts of the belly." As if to say, The illumination of Divine inspiration, when it comes into a man's mind, shews it to itself by illuminating it, whereas before the coming of the Holy Spirit it both could entertain bad thoughts and knew not how to estimate them. Then, the blueness of a wound cleanses away evil, and stripes in the secret parts of the belly, because when we are smitten outwardly, we are recalled, silent and afflicted, to memory of our sins, and bring back before our eyes all our past evil deeds, and through what we suffer outwardly we grieve inwardly the more for what we have done. Whence it comes to pass that in the midst of open wounds of the body the secret stripe in the belly cleanses us more fully, because a hidden wound of sorrow heals the iniquities of evil-doing.”

“The blueness of a wound cleanses away evil, etc. For when we are struck outwardly, we are silently and afflictedly recalled to the memory of our sins. And through what we suffer outwardly, we grieve more inwardly for what we have done; thus it happens that among the open wounds of the body, the secret wound of the belly cleanses us more, because it heals the wickedness of a depraved work, the hidden wound of sorrow. For indeed the belly is often taken to mean the mind, because just as the belly consumes food, thus the mind by pondering digests cares.”