We must suffer. Our five sense are dulled by inordinate pleasure. Penance makes them keen, gives them back their natural vitality, and more. Penance clears the eye of conscience and of reason. It helps think clearly, judge sanely. It strengthens the action of our will.
Thomas MertonConsequently, the truth of God lives in our souls more by the power of superior moral courage than by the light of an eminent intelligence. Indeed, spiritual intelligence itself depends on the fortitude and patience with which we sacrifice ourselves for the truth, as it is communicated to our lives concretely in the providential will of God
Thomas Merton