Timaeus. In the first stage of his philosophy Plato attributed Ideas to
all things, at any rate to all things which have classes or common notions:
these he supposed to exist only by participation in them. In the later
Dialogues he no longer included in them manufactured articles and ideas of
relation, but restricted them to 'types of nature,' and having become
convinced that the many cannot be parts of the one, for the idea of
participation in them he substituted imitation of them. To quote Dr.
Jackson's own expressions,--'whereas in the period of the Republic and the
Phaedo, it was proposed to pass through ontology to the sciences, in the
period of the Parmenides and the Philebus, it is proposed to pass through
the sciences to ontology': or, as he repeats in nearly the same words,--
'whereas in the Republic and in the Phaedo he had dreamt of passing through
ontology to the sciences, he is now content to pass through the sciences to
ontology.'

This theory is supposed to be based on Aristotle's Metaphysics, a passage
containing an account of the ideas, which hitherto scholars have found
impossible to reconcile with the statements of Plato himself. The
preparations for the new departure are discovered in the Parmenides and in
the Theaetetus; and it is said to be expressed under a different form by
the (Greek) and the (Greek) of the Philebus. The (Greek) of the Philebus
is the principle which gives form and measure to the (Greek); and in the
'Later Theory' is held to be the (Greek) or (Greek) which converts the
Infinite or Indefinite into ideas. They are neither (Greek) nor (Greek),
but belong to the (Greek) which partakes of both.

With great respect for the learning and ability of Dr. Jackson, I find
myself unable to agree in this newly fashioned doctrine of the Ideas, which
he ascribes to Plato. I have not the space to go into the question fully;
but I will briefly state some objections which are, I think, fatal to it.