ABSTRACT
The most fundamental of the group of ideas of which we are to review the history appears first in Plato; and nearly all that follows might therefore serve as an illustration of a celebrated remark of Professor Whitehead's, that 'the safest general characterization of the European philosophical tradition is that it consists in a series of footnotes to Plato'. The interpreters of Plato in both ancient and modern times have endlessly disputed over the question whether this conception of the absolute Good was for him identical with the conception of God. There are in the Platonic dialogues occasional intimations that the Ideas, and therefore their sensible counterparts, are not all of equal metaphysical rank or excellence; but this conception not only of existences but of essences as hierarchically ordered remains in Plato only a vague tendency, not a definitely formulated doctrine.
