The Idols of the Cave are the idols of the individual man. For everyone (besides the errors common to human nature in general) has a cave or den of his own, which refracts and discolors the light of nature; owing either to his own proper and peculiar constitution, or to his education and conversation with others, or to the books he reads, and the authority of those whom he esteems and admires, or to the differences of impressions, accordingly as they happen to be received 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 a thing variable and full of perturbation, and governed as it were by chance.
Empiricism, scientific method