I came across an old legend about three cowboys crossing the desert on horseback by night. Suddenly, as they reached a rocky spot, a voice came from heaven and commanded them: "Friends, pick up some pebbles, put them in your pockets and do not look at them till morning." The men looked at each other in astonishment and began to do as they were told. The voice went on to promise that if they obeyed, they would be both glad and sad. The perplexed men put a few pebbles each in their pockets and went on their way.