One night in ancient times, three horsemen were riding across a desert. As they crossed the dry bed of a river, out of the darkness a voice called, “Halt!” They obeyed. The voice then told them to dismount, to pick up handfuls of pebbles, put the pebbles in their pockets, and remount. The horsemen followed the instruction.
The voice then said, “If you have done as I commanded, tomorrow at sunup you will be both glad and sorry.” The horsemen rode on. When the sun rose, they reached into their pockets and found that a miracle had happened. The pebbles had been transformed into diamonds and other precious stones.
The horsemen remembered the warning that they would be both glad and sorry. They were glad they had taken some pebbles, sorry they had not taken more.