The foregoing diagram, borrowed from Whewell, with some modifications and additions we have ventured to make, exhibits a perfect view of the Platonic scheme of the cognitive powers--the faculties by which the mind attains to different degrees of knowledge, "having more or less certainty, as their objects have more or less truth." [535]
1st. SENSATION (αἴσθησις).--This term is employed by Plato to denote the passive mental states or affections which are produced within us by external objects through the medium of the vital organization, and also the cognition or vital perception or consciousness [536] which the mind has of these mental states.
2d. PHANTASY (φαντασία).--This term is employed to describe the power which the mind possesses of imagining or representing whatever has once been the object of sensation. This may be done involuntarily as "in dreams, disease, and hallucination," [537] or voluntarily, as in reminiscence. Φαντάσµατα are the images, the life-pictures (ζωγράφηµα) of sensible things which are present to the mind, even when no external object is present to the sense.
[Footnote 535: ][ (return) ] "Republic," bk. vii. ch. xix.
[Footnote 536: ][ (return) ] "In Greek philosophy there was no term for 'consciousness' until the decline of philosophy, and in the latter ages of the language. Plato and Aristotle, to say nothing of other philosophers, had no special term to express the knowledge which the mind has of the operation of its own faculties, though this, of course, was necessarily a frequent matter of consideration. Intellect was supposed by them to be cognizant of its own operations.... In his 'Theætetus' Plato accords to sense the power of perceiving that it perceives."--Hamilton's "Metaphysics," vol. i. p. 198 (Eng. ed.).
[Footnote 537: ][ (return) ] "Theætetus," § 39.
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: ][ (return) ] Alcinous, "Introduction to the Doctrine of Plato," p. 247.
[Footnote 539: ][ (return) ] "Timæus," § 14.