Thomas Aquinas

“ For, although the stain of sin is not washed out without contrition, yet this sacrament, by the grace which it bestows, makes the movement of the free will towards sin to be one of contrition, just as may occur in the Eucharist and Confirmation. Again it diminishes the debt of temporal punishment; and this indirectly, in as much as it takes away weakness, for a strong man bears the same punishment more easily than a weak man. ”

“ I answer that, Just as Baptism causes a spiritual cleansing from spiritual stains by means of a bodily washing, so this sacrament causes an inward healing by means of an outward sacramental healing: and even as the baptismal washing has the effect of a bodily washing, since it effects even a bodily cleansing, so too, Extreme Unction has the effect of a bodily remedy, namely a healing of the body. ”

“ Now Extreme Unction does not remit the stain without contrition, and this remits sin even without Unction; nor does it remit the punishment, for if the recipient recover, he is still bound to fulfill the satisfaction enjoined; nor does it take away the remnants of sin, since the dispositions remaining from preceding acts still remain, as may easily be seen after recovery. Therefore remission of sins is by no means the effect of Extreme Unction. ”