Note Footnote 1: — INTRODUCTION.

Francis Bacon drew attention to these inner perverting influences, these universal sources of erroneous belief, in his De Augmentis and again in his Novum Organum, under the designation of Idola, (εἴδωλα) deceptive appearances of truth, illusions. His classification of Idola—Idola Tribus, illusions common to all men, illusions of the race; Idola Specus, personal illusions, illusions peculiar to the "den" in which each man lives; Idola Fori, illusions of conversation, vulgar prejudices embodied in words; Idola Theatri, illusions of illustrious doctrine, illusions imposed by the dazzling authority of great names—is defective as a classification inasmuch as the first class includes all the others, but like all his writings it is full of sagacious remarks and happy examples. Not for the sake of novelty, but because it is well that matters so important should be presented from more than one point of view, I shall follow a division adapted from the more scientific, if less picturesque, arrangement of Professor Bain, in his chapter on the Fallacious Tendencies of the Human Mind.1