When I hear someone expressing a definite opinion about something which I have reason to believe he knows little or nothing, I think of an experience I had when I stopped a Quaker on the streets of Philadelphia and asked him the time of day. He took out his watch, examined it carefully, and then in a slow, emphatic tone of voice he said “Well Sir, According to this alleged time piece it appears to be approximately one minute and ten seconds past twelve o’clock.”

I was particularly impressed by the care with which this Quaker identified the source of his information which he was passing on to me, and I often thought afterward how beneficial it would be if all people who express opinions or give out information would take the time to identify the source from which they were able to speak.
I cannot influence all people to engage in this sort of safe thinking but I can suggest that you give it careful consideration in connection with this visit on the subject of Accurate Thinking.
Now I shall give you a simple rule which may help you avoid being misled by unsound opinions expressed by other people. When you hear someone make a statement which your reason cannot accept as being sound, or which you question or should for safety-sake question for any reason whatsoever, ask a simple four word question: “HOW DO YOU KNOW?” Then stand firm on that question and either force the speaker to identify the source from which he got the information he is endeavoring to pass on as FACTS, or reject the statement entirely, as if it had not been made. And do this, no matter who is speaking or what may be his reputations for truth and veracity.
Remember, you were given, as your richest birthright, the privilege of controlling your own thoughts. Therefore, treat this Divine Gift with the profound respect to which it is entitled and Do not allow anyone to do your thinking for you or to influence your thinking in any manner whatsoever except by the rules of Accurate Thinking I am passing on to you.
Follow this procedure regardless of what people think or say about your method of thinking. If they wish to call you a cynic or a Doubting Thomas let that be their misfortune, but for your own good, go right on thinking by rules which will save you from many mistakes and tragedies throughout your life.
Source: Master Key to Riches Video Series. Film: Accurate Thinking. The Napoleon Hill Foundation.