Journeys derive their meaning from arrival at their destination; retrospectively, they appear worthwhile. On the road it is different, especially if there is some uncertainty about reaching the goal. The hope which impels us forward is a hope that cannot yet see its own object (Rom 8:24)– we are traveling blind. We must expect that the length and hardship of the journey will sometimes seem impossible to bear. We will be tempted to be disheartened, to allow ourselves to lose the sharp focus of our discipleship and drift into distracting diversions. Inevitably, given the complex demands discipleship places upon us, there will be failures, misjudgments, and periods of stagnation. In the context of the whole journey and from the standpoint of eternity these are trifling, whatever their magnitude. Locked in time and space, we cannot see this and so we are tempted to lose our nerve and give up our search for God. ”This saying is [too] hard; who can hear it?” (Jn 6:60). It is easy to rationalize such apostasy; but there is danger that something in our own spirits dies when we settle for second best. Those who remain become plodders, perhaps. They no longer trust in their own virtuosity, but let go to allow God brilliantly to bring to perfection the work begun, but in a manner that transcends human assessment or intelligence.
(Casey, Fully Human Fully Divine, 168)