which they are supported or with which they can be compared.
IV.There is another subject to which I must briefly call attention, lest I should seem to have overlooked it.Dr.Henry Jackson, of Trinity College, Cambridge, in a series of articles which he has contributed to the Journal of Philology (1881-6; Vol.x.132-150, 253-293; xi.287- 331 ; xiii.1-40 ; xiv.173-230, extending to about 200 pages), has put forward an entirely new explanation of the Platonic ' Ideas.' He supposes that in the mind of Plato they took, at different times in his life, two essentially different forms :— an earlier one which is found chiefly in the Republic and the Phaedo, and a later, which appears in the Theaetetus, Philebus, Sophist, Politicus, Parmeni- des, 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 sup- posed 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 (xi.292).To quote Dr.Jackson's own expressions (x.297), — ' 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 (xi.320), — ' whereas in the Re- public 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
