once upon a time, there was an artist with moderate skill level. once he thought of testing his skill level, so painted a beautiful picture and exhibited in a busy street with a note "if u find any mistake please mark on the painting". When artist came back in evening to check the response, he could'nt identify the picture bcos its full of marking.. the guy was very much depressed. His intelligent uncle suggested to draw another painting and with a changed note " if u find any mistake please CORRECT it" The artist followed the suggestion. 2 his surprise when he checked the painting in the evening there wasnt a single marking... so artist was very happy.. moral of the story.. i dont know