Very often in expressing one's opinion -- rather in giving one's idea about another -- one places himself before others for examination. As soon as a person has expressed his opinion all others know what note of life he strikes -- that is, those who have the knowledge to know it. This does not mean that one must not have an opinion. It would be like saying one must not have a mind. Where there is a mind there will be an opinion. Does it not very often happen to an intelligent person that immediately after having expressed his opinion he finds out how foolish he has been in expressing his opinion? Often through nervousness, through lack of control over oneself, or through lack of patience one expresses one's opinion. That opinion is valuable which comes by invitation.