The Barrel Principle

The capacity of a barrel is determined not by the longest wooden bar, but by the shortest one. This is the famous Barrel Principle.

Determine the success or failure of a person's enterprise is not strengh or superiority, but defects or weaknesses.
In everyday life, some people get used to enjor their own strengh, but ignore that something may be not good enough. This kind of shortage may cause the failure of whole cause in the critical moment.