Thomas Aquinas

“ One is in the reason, and is displeasure at the sin committed. This can be so slight as not to suffice for real contrition, e.g. if a sin were less displeasing to a man, than separation from his last end ought to be; just as love can be so slack as not to suffice for real charity. The other sorrow is in the senses, and the slightness of this is no hindrance to real contrition, because it does not, of itself, belong essentially to contrition, but is connected with it accidentally: nor again is it under our control. ”

“ Just as inward joy redounds into the outward parts of the body, so does interior sorrow show itself in the exterior members: wherefore it is written (Prov. 17:22) : "A sorrowful spirit drieth up the bones." ”

“ A man cannot be sure that his contrition suffices for the remission of both punishment and guilt: wherefore he is bound to confess and to make satisfaction, especially since his contrition would not be true contrition, unless he had the purpose of confessing united thereto: which purpose must also be carried into effect, on account of the precept given concerning confession. ”