Discipline (or mortification) puts back in its place that something in us which should serve but wants to rule.  That is to say, it restores that order which has been upset by the Fall.  It puts reason back again as the rule of life; it makes us calm and reasonable.  If it does not tend to do this, then it is stupid and pointless.

  Mortification of the body is above all a symbol. It stands for that chastisement which the will should have the courage to inflict on all the powers of the soul, in order to submit them, along with itself, to God, and so re-establish in Him that shattered unity of our human nature.  That is the goal, most sublime and blessed, of all our efforts: a goal which is well worth the journeying, however hard it may be.