t. SENSATION (aisthesis).--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 (phantasia).--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. Phantasmata are the images, the life-pictures (zographena)
of sensible things which are present to the mind, even when no external
object is present to the sense.

[Footnote 535: "Republic," bk. vii. ch. xix.]

[Footnote 536: "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
'Theaetetus' Plato accords to sense the power of perceiving that it
perceives."--Hamilton's "Metaphysics," vol. i. p. 198 (Eng. ed.).]

[Footnote 537: "Theaetetus," Sec. 39.]

The conjoint action of these two powers results in what Plato calls
_opinion_ (doxa). "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 dixa of Plato,
therefore answers to the experience, or the _empirical knowledge_ of
modern philosophy, which is concerned only with appearances (phenomena),
and no