Three attempts to explain the new definition of knowledge still remain to
be considered. They all of them turn on the explanation of logos. The
first account of the meaning of the word is the reflection of thought in
speech--a sort of nominalism 'La science est une langue bien faite.' But
anybody who is not dumb can say what he thinks; therefore mere speech
cannot be knowledge. And yet we may observe, that there is in this
explanation an element of truth which is not recognized by Plato; viz. that
truth and thought are inseparable from language, although mere expression
in words is not truth. The second explanation of logos is the enumeration
of the elementary parts of the complex whole. But this is only definition
accompanied with right opinion, and does not yet attain to the certainty of
knowledge. Plato does not mention the greater objection, which is, that
the enumeration of particulars is endless; such a definition would be based
on no principle, and would not help us at all in gaining a common idea.
The third is the best explanation,--the possession of a characteristic
mark, which seems to answer to the logical definition by genus and
difference. But this, again, is equally necessary for right opinion; and
we have already determined, although not on very satisfactory grounds, that
knowledge must be distinguished from opinion. A better distinction is
drawn between them in the Timaeus. They might be opposed as philosophy and
rhetoric, and as conversant respectively with necessary and contingent
matter. But no true idea of the nature of either of them, or of their
relation to one another, could be framed until science obtained a content.
The ancient philosophers in the age of Plato thought of science only as
pure abstraction, and to this opinion stood in no relation.

Like Theaetetus, we have attained to no definite result. But an
interesting phase of ancient philosophy has passed before us. And the
negative result is not to be despised. For on certain subjects, and in
certain states of knowledge, the work of negation or clearing the ground