“It is necessary to caution the analyst against overconfidence in the practical utility of his findings. It is always good to know the truth, but it may not always be wise to act upon it, particularly in Wall Street. And it must always be remembered that the truth that the analyst uncovers is first of all not the whole truth and, secondly, not the immutable truth. The result of his study is only a more nearly correct version of the past. His information may have lost its relevance by the time he acquires it, or in any event by the time the market place is finally ready to respond to it.”
—Benjamin Graham and David Dodd (Security Analysis: Sixth Edition).