Wherever and whenever the authority of ancient traditions is broken down, the doctrine that one man’s opinion is as good as another’s immediately takes its place; or rather the doctrine in question is a survival of traditionalism in an extremely pulverised form. And when we are told that the majority must be right—which is a very different principle from holding that the majority should be obeyed—we may take it as a sign that the loose particles are beginning to coalesce again. The substitution of an individual for a universal standard of truth is, according to Plato, a direct consequence of the theory which identifies knowledge with sense-perception. It is, at any rate, certain that the most vehement assertors of the former doctrine are also those who are fondest of appealing to what they and their friends have seen, heard, or felt; and the more educated among them place enormous confidence in statistics. They are also fond of repeating the adage that an ounce of fact is worth a ton of theory, without considering that theory alone can furnish the balance in which facts are weighed. Plato does not go very deep into the _rationale_ of observation, nor in the infancy of exact science was it to be expected that he should. He fully recognised the presence of two factors, an objective and a subjective, in every sensation, but lost his hold on the true method in attempting to trace a like dualism through the whole of consciousness. Where we should distinguish between the mental energies and the physical processes underlying them, or between the elements respectively contributed to every cognition by immediate experience and reflection, he conceived the inner and outer worlds as two analogous series related to one another as an image to its original.