r one which is found chiefly in the Republic and the Phaedo, and
a later, which appears in the Theaetetus, Philebus, Sophist, Politicus,
Parmenides, 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.

(1) First, the foundation of his argument is laid in the Metaphysics of
Aristotle. But we cannot argue, either from the Metaphysics, or from any
other of the philosophical treatises of Aristotle, to the dialogues
of Plato until we have ascertained the relation in which his so-called
works stand to the philosopher himself. There is of course no doubt
of th