Certain common-sense consideration relate to the criterion of normal or standard results mentioned above. Our basic thesis is this: If the investor is to rely chiefly on the advice of others in handling his funds, then either (a) he must limit himself and his advisers strictly to standard, conservative, and even un imaginative forms of investment or (b) he must have an unusually intimate and favorable knowledge of the person who is going to direct his funds into other channels; for only to the extent that the investor himself grows in knowledge and competence and therefore becomes qualified to pass independent judgement on the recommendations of others can he be receptive to less conventional suggestions from his advisers.

Chapter III, The Investor and His Advisers, p. 46 - The Intelligent Investor: The Classic Text on Value Investing (1949)