Two labourers were working for the city. One would dig a hole; dig, dig, dig. The other would come behind him and fill the hole; fill, fill, fill. These two men worked furiously. One digging a hole, the other filling it up again.
A man watching was impressed at how hard these men were working, but couldn't understand what they were doing. Finally he had to ask. "I appreciate how hard you work, but what are you doing? You dig a hole and your partner comes behind you and fills it up again!"
The hole digger replied, "Oh yeah, the guy who plants the trees is sick today."