Once there was a little boy who had a bad temper. His father gave him a bag of nails and told him that every time he lost his temper，he must hammer a nail into the fence
The first day the boy hammered 37 nails into the fence. Over the next few weeks，as he learned to control his anger，the number of nails hammered daily dwindled down．He discovered it was easier to hold his temper than to drive those nails into the fence．
Finally the day came when the boy didn’t lose his temper at all．He told his father about it and the father suggested that the boy now pull out one nail for each day that he was able to hold his temper．
The days passed and one day the young boy told his father that all the nails were gone．The father took his son by the hand and led him to the fence．The fence would never be the same．“When you say things in anger，they leave a scar just like those nails，”his father said．