acknowledged to be the
creations of the mind herself, working upon the feelings or impressions
of sense. In this manner Plato describes the process of acquiring them,
in the words 'Knowledge consists not in the feelings or affections
(pathemasi), but in the process of reasoning about them (sullogismo).'
Here, is in the Parmenides, he means something not really different
from generalization. As in the Sophist, he is laying the foundation of a
rational psychology, which is to supersede the Platonic reminiscence of
Ideas as well as the Eleatic Being and the individualism of Megarians
and Cynics.

V. Having rejected the doctrine that 'Knowledge is perception,' we now
proceed to look for a definition of knowledge in the sphere of opinion.
But here we are met by a singular difficulty: How is false opinion
possible? For we must either know or not know that which is presented
to the mind or to sense. We of course should answer at once: 'No; the
alternative is not necessary, for there may be degrees of knowledge; and
we may know and have forgotten, or we may be learning, or we may have a
general but not a particular knowledge, or we may know but not be able
to explain;' and many other ways may be imagined in which we know and do
not know at the same time. But these answers belong to a later stage of
metaphysical discussion; whereas the difficulty in question naturally
arises owing to the childhood of the human mind, like the parallel
difficulty respecting Not-being. Men had only recently arrived at the
notion of opinion; they could not at once define the true and pass
beyond into the false. The very word doxa was full of ambiguity, being
sometimes, as in the Eleatic philosophy, applied to the sensible world,
and again used in the more ordinary sense of opinion. There is no
connexion between sensible appearance and probability, and yet both
of them met in the word doxa, and could hardly be disengaged from one
another in the mind of the Greek living in the fifth or fourth century
B.C. To this was often added, as at the end of the fifth book of the
Republic, the idea of relation, which is equally distinct from either of
them; also a fourth notion, the conclusion of the dialectical process,
the making up of the mind after she has been 'talking to herself'
(Theat.).

We are not then surprised that the sphere of opinion and of Not-being
should be a dusky, half-lighted place (Republic), belonging neither
to the old world of sense an