Holmes: You mustn't allow your failure to discourage you.
Watson: Didn't fail. Not discouraged.
Holmes: You didn't solve the case, but you did notice the incongruity of the scuff marks. The next step is learning to extrapolate your way to the truth. Detection is not just a skill, Watson. It's a point of view. You must train yourself to be alert to the bizarre, the unusual, that which has no place in any given picture.