There are four classes of Idols which beset men’s minds. To these for distinction’s sake I have assigned names─calling the first class Idols of the Tribe; the second, Idols of the Cave; the third, Idols of the Marketplace; the fourth, Idols of the Theatre.
The formulation of ideas and axioms by true induction is no doubt the proper remedy to be applied for the keeping off and the clearing away of idols. To point them out, however is of great use; for the doctrine of Idols is to the interpretation of Nature what the doctrine of the refutation of Sophisms is to common logic.
The Idols of the Tribe have their foundation in human nature itself, and in the tribe or race of men. For it is a false assertion that the the sense of man is the measure of things. On the contrary, all perceptions as well of the sense of the mind are according to the measure of the universe. And the human understanding is like a false mirror, which, receiving rays irregularly, distorts and discolours the nature of things by mingling its own nature with it.
The Idols of the Cave are the idols of the individual man. For everyone (besides the errors common to human nature in general) have a cave or den of his own, which refracts and discolours the light of nature; owing either to his own proper and peculiar nature; or to his education and conversation with others; or to the reading of books, and the authority of those 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; or the like. So that the spirit of man (according as it is meted out to different individuals) is in fact a thing variable and full of perturbation, and governed as it were by chance. Whence it was well observed by Heraclitus that men look for sciences in their own lesser worlds, and not in the greater common world.
There are also idols formed by the intercourse and association of men with each other, which I call Idols of the Marketplace, on account of the commerce and consort of the men there. For it is by discourse that men associate; and words are imposed according to the apprehension of the vulgar. And therefore the ill and unfit choice of words wonderfully obstructs the understanding. Nor do the definitions or explanations wherewith in some things learned men are wont to guard and defend themselves, by any means set the matter right. But words plainly force and overrule the understanding, and throw all into confusion, and lead men away into numberless empty controversies and idle fancies.
Lastly, there are idols which have immigrated into men’s minds from the various dogmas of philosophies, and also from wrong laws of demonstration. These I call Idols of the Theatre; because in my judgment all the received systems are but so many stage-plays, representing worlds of their own creation after an unreal and scenic fashion. Nor is it only of the systems now in vogue, or only of the ancient sects and philosophies, that I speak; for many more plays of the same kind may yet be composed and in like artificial manner set forth; seeing that errors the most widely different have nevertheless causes for the most part alike. neither again do I mean this only of entire systems, but also of many principles and axioms in science, which by tradition, credulity, and negligence have come to be received.
Eds: J.L. Golden, G.F. Berquist, W.E. Coleman J. M. Sproule; The Rhetoric of Western Thought From the Mediterranean World to the Global Setting Eighth Ed. (Kendall/Hunt Publishing Company Dubuque Iowa ©1976- 2004) p. 150