'a longer and a shorter way', and of a way in which his disciple Glaucon
'will be unable to follow him'; also of a way of Ideas, to which he still
holds fast, although it has often deserted him (Philebus, Phaedo), and
although in the later dialogues and in the Laws the reference to Ideas
disappears, and Mind claims her own (Phil.; Laws). No hint is given of
what Plato meant by the 'longer way' (Rep.), or 'the way in which Glaucon
was unable to follow'; or of the relation of Mind to the Ideas. It might
be said with truth that the conception of the Idea predominates in the
first half of the Dialogues, which, according to the order adopted in this
work, ends with the Republic, the 'conception of Mind' and a way of
speaking more in agreement with modern terminology, in the latter half.
But there is no reason to suppose that Plato's theory, or, rather, his
various theories, of the Ideas underwent any definite change during his
period of authorship. They are substantially the same in the twelfth Book
of the Laws as in the Meno and Phaedo; and since the Laws were written in
the last decade of his life, there is no time to which this change of
opinions can be ascribed. It is true that the theory of Ideas takes
several different forms, not merely an earlier and a later one, in the
various Dialogues. They are personal and impersonal, ideals and ideas,
existing by participation or by imitation, one and many, in different parts
of his writings or even in the same passage. They are the universal
definitions of Socrates, and at the same time 'of more than mortal
knowledge' (Rep.). But they are always the negations of sense, of matter,
of generation, of the particular: they are always the subjects of
knowledge and not of opinion; and they tend, not to diversity, but to
unity. Other entities or intelligences are akin to them, but not the same
with them, such as mind, measure, limit, eternity, essence (Philebus;
Timaeus): these and similar terms appear to express the same truths from a
different point of view, and to belong to the same sphere with them. But
we are not justified, therefore, in attempting to identify them, any more