Gary Inrig, A Call to Excellence, (Victor Books, a division of SP Publ., Wheaton, Ill; 1985), p. 98
A large group of European pastors came to one of D. L. Moody's Northfield Bible Conferences in Massachusetts in the late 1800s. Following the European custom of the time, each guest put his shoes outside his room to be cleaned by the hall servants overnight. But of course this was America and there were no hall servants.
Walking the dormitory halls that night, Moody saw the shoes and determined not to embarrass his brothers. He mentioned the need to some ministerial students who were there, but met with only silence or pious excuses. Moody returned to the dorm, gathered up the shoes, and, alone in his room, the world's only famous evangelist began to clean and polish the shoes. Only the unexpected arrival of a friend in the midst of the work revealed the secret.
When the foreign visitors opened their doors the next morning, their shoes were shined. They never know by whom. Moody told no one, but his friend told a few people, and during the rest of the conference, different men volunteered to shine the shoes in secret. Perhaps the episode is a vital insight into why God used D. L. Moody as He did. He was a man with a servant's heart and that was the basis of his true greatness.