“He told us so” is reported to have been a common remark among the disciples of Pythagoras. And to the present time disciples of any master have not failed to quote their master. It is not even necessary to be a master in order to be a prophet. A strong voice, significant gesticulation, and impressive speech are sufficient to guide the belief of the masses of the people. When everybody holds a certain belief and gives expression to it, no member of the crowd can escape the influence of the constant repetition of the thought. I cannot help believing what my friends or my associates in a profession believe. Even if I begin to reflect on the reasonableness of accepting as a truth what I have merely often heard, I can hardly free myself of the belief. Is it not highly improbable that all of them should have been led into error without noticing it? On the consensus of everybody, philosophers have frequently founded their highest doctrines. Cicero calls it the voice of nature. On the other hand, narrow-minded people often attempt to fight a truth which they dislike by pointing out partial disagreements among its adherents. But the belief in statements which are neither proved nor disproved is not always based on authority; that is, produced by emphatic and often-repeated expression of these statements by the people among whom we live. It is frequently the result of strong and deep-seated needs of the human mind. As long as these needs make themselves felt, they call up in the mind ideas of remedies and means in harmony with analogous experiences; and unless these remedies and means are contradicted by other experiences, they are believed. One may call this, in distinction from the authoritative belief, practical or emotional belief. Every one believes in his own destiny. Every mother believes in her son. Napoleon believed in his star. A general who doubts if he is going to win the impending battle has already half lost it. Can he prove it, that is, can he interpret what he sees and what is reported to him in such a manner that the idea of his winning the battle cannot appear in his mind without the idea of reality? He is probably very far from giving his experiences such an interpretation. Of course, he will do his best in order to make victory come his way. But his knowledge constantly informs him that the outcome is dubious. Yet this knowledge does not keep him from believing that it is not dubious. He cannot help believing it. His whole existence depends on this belief. His honor, his future career, his nation, all is lost unless he wins. The idea of loss is impossible. It is inhibited by the idea of success, by that idea which alone can give him the prudence and presence of mind that are needed.