truths, we may be sure that furious controversy would have attended the issue, and some way found to overthrow the demonstration. That two and two make four would have been denied had any strong emotion been excited against the proposition. "Men," said Whateley, "are much more anxious to have truth on their side than to be on the side of truth." And the danger is greater because we are frequently not aware of the bias given by feeling. There are cases in plenty where men more or less consciously and deliberately espouse "sciences as one would," but there are many others in which the emotional interference is insidious and obscure. "Numberless, in short, are the ways, and sometimes imperceptible, in which the feelings color and infect the understanding."
These Idols of the Tribe are of course inherent in our intellectual constitution, and are ineradicable. The simple consideration that all knowledge is relative—that by no effort and under no circumstances can we escape beyond the conditions and limitations of our own minds—suffices to show that intelligence must ever mix up its own nature with the nature of things, though this fact need not make us doubt the validity of knowledge as is sometimes hastily inferred. For the rest, clear recognition of these common obstacles to thought should put us in the way of anticipating and withstanding their more serious effects. In practice it must be our object to maintain watchfulness and a careful skepticism; to test evidence and check passion; to cultivate candor, flexibility, and alertness of mind; to avoid loose generalizations; and to be ever ready to accept, revise, reject. Above all must we steadily resist the seductions of what is called common sense, and overcome that mental inertness which too often leads us to drift unthinking along the current of popular opinion.[1]
But, in addition to errors arising from the common intellectual nature of men, there are others, the sources of which are to be found in the idiosyncrasies of the individual mind. These Bacon calls Idols of the Cave;[2] for every one, he says, "has a cave or den of his own, which refracts and discolors the light of Nature, owing either to his own proper and peculiar nature; or to his education and conversation with others; or to his reading of books, and the authority of those whom he esteems and admires; or to the differences of impressions, accordingly as they take place in a mind preoccupied and predisposed, or in a mind indifferent and settled; and the like." This summary is comprehensive enough to indicate the character and point to some of the causes of individual aberrations of judg-
