circulate untested. Even more disastrous, perhaps, in the long run, is the power of prepossessions. When once, says Bacon, the human understanding has "adopted an opinion (either as being the received opinion, or as being agreeable to itself)" it straightway "draws all things else to support and agree with it." Illustrations may be found in every direction. Note, for instance, the vitality, even in the teeth of positive disproof, of many long-accepted and often-challenged ideas—belief in dreams, omens, prophecies, in providential visitations and interpositions, in the significance of coincidences, in popular saws about natural phenomena, in quacks and quackery, in old wives' tales, "vulgar and pseudo-scientific. The story of witchcraft is only another example of the same kind, though written large in the chronicles of the world in letters of fire and blood; the human understanding had "adopted" a belief in witches, and drew "all things else to support and agree with it." In all such cases of prepossession the mind obstinately dwells on every detail that favors its accepted conclusions, while disregarding or depreciating everything that tells against them; it is always, in Bacon's phrase, "more moved and excited by affirmatives than by negatives." Thus, we hear much of the one dream that is fulfilled, and of the ninety and nine that are unfulfilled—nothing. Bacon illustrates this perversity by the well-known anecdote of the ancient cynic, which may be left to convey its own moral: "And therefore it was a good answer that was made by one who, when they showed him hanging in a temple a picture of those who had paid their vows as having escaped shipwreck, and would have him say whether he did not now acknowledge the power of the gods—'Ay,' asked he again, 'but where are they painted that were drowned after their vows?'"
Finally, among these Idols of the Tribe we must include the disturbance caused by the play of feeling upon the mind." The human understanding is no dry light, but receives an infusion from the will and affections, whence proceed sciences which may be called 'sciences as one would.'" We all know, to our cost, how passion will warp judgment; how" difficult it is to see clearly when the emotions are thoroughly aroused; how tenaciously men cling to opinions they are familiar with, or would fain have to be true; how fiercely they contest ideas that are unfamiliar or repugnant. Had it been contrary to the interest of authority, observed shrewd old Hobbes, that the three angles of a triangle should be equal to two angles of a square, the fact would have been, if not disputed, yet suppressed.[1] Similarly, if the passions of men had been called into play over the most clearly demonstrable of abstract mathematical
