The scholar was pointing at the shadowy figure of a peasant leading a donkey homeward at twilight. The man's feet were wrapped in sackcloth, and the mud had caked about them so that he seemed scarcely able to lift them. But he trudged ahead one slogging step after another, resting half a second between footfalls. He seemed too weary to scrape off the mud.
"He doesn't ride the donkey," Thon Taddeo stated, "because this morning the donkey was loaded down with corn. It doesn't occur to him that the packs are empty now. A what is good enough for the morning is also good enough for the afternoon."  -  A Canticle for Leibowitz, Walter M. Miller, Jr.