The conjoint action of these two powers results in what Plato calls _opinion_ (δόξα). "Opinion is the complication of memory and sensation. For when we meet for the first time with a thing perceptible by a sense, and a sensation is produced by it, and from this sensation a memory, and we subsequently meet again with the same thing perceived by a sense, we combine the memory previously brought into action with the sensation produced a second time, and we say within ourselves [this is] Socrates, or a horse, or fire, or whatever thing there may be of such a kind. Now this is called _opinion_, through our combining the recollection brought previously into action with the sensation recently produced. And when these, placed along each other, agree, a true opinion is produced; but when they swerve from each other, a false one."[538] The δόξα of Plato, therefore answers to the experience, or the _empirical knowledge_ of modern philosophy, which is concerned only with appearances (phenomena), and not with absolute realities, and can not be elevated to the dignity of _science_ or real knowledge. We are not from hence to infer that Plato intended to deny all reality whatever to the objects of sensible experience. These transitory phenomena were not real existences, but they were _images_ of real existences. The world itself is but the image, in the sphere of sense, of those ideas of Order, and Proportion, and Harmony, which dwell in the Divine Intellect, and are mirrored in the soul of man. "Time itself is a moving image of Eternity."[539] But inasmuch as the immediate object of sense-perception is a representative image generated in the vital organism, and all empirical cognitions are mere "conjectures" (εἰκασίαι) founded on representative images, they need to be certified by a higher faculty, which immediately apprehends real Being (τὸ ὄν). Of things, as they are in themselves, the senses give us no knowledge; all that in sensation we are conscious of is certain affections of the mind (πάθος); the existence of self, or the perceiving subject, and a something external to self, a perceived object, are revealed to us, not by the senses, but by the reason. [Footnote 538: Alcinous, "Introduction to the Doctrine of Plato," p. 247.] [Footnote 539: "Timæus," § 14.]