Objection 1. It would seem that the sorrow of contrition cannot be too great. For no sorrow can be more immoderate than that which destroys its own subject. But the sorrow of contrition, if it be so great as to cause death or corruption of the body, is praiseworthy. For Anselm says (Orat. lii): "Would that such were the exuberance of my inmost soul, as to dry up the marrow of my body"; and Augustine [De Contritione Cordis, work of an unknown author] confesses that "he deserves to blind his eyes with tears." Therefore the sorrow of contrition cannot be too great.
Objection 2. Further, the sorrow of contrition results from the love of charity. But the love of charity cannot be too great. Neither, therefore, can the sorrow of contrition be too great.
Objection 3.On the contrary, Every moral virtue is destroyed by excess and deficiency. But contrition is an act of a moral virtue, viz. penance, since it is a part of justice. Therefore sorrow for sins can be too great.
I answer that, Contrition, as regards the sorrow in the reason, i.e. the displeasure, whereby the sin is displeasing through being an offense against God, cannot be too great; even as neither can the love of charity be too great, for when this is increased the aforesaid displeasure is increased also. But, as regards the sensible sorrow, contrition may be too great, even as outward affliction of the body may be too great. In all these things the rule should be the safeguarding of the subject, and of that general well-being which suffices for the fulfillment of one's duties; hence it is written (Romans 12:1): "Let your sacrifice be reasonable [Vulgate: 'Present your bodies... a reasonable sacrifice']."
Reply to Objection 1. Anselm desired the marrow of his body to be dried up by the exuberance of his devotion, not as regards the natural humor, but as to his bodily desires and concupiscences. And, although Augustine acknowledged that he deserved to lose the use of his bodily eyes on account of his sins, because every sinner deserves not only eternal, but also temporal death, yet he did not wish his eyes to be blinded.
Reply to Objection 2. This objection considers the sorrow which is in the reason: while the Third considers the sorrow of the sensitive part.
Source: Summa Theologica (New Advent)