To sum up: the Parmenides of Plato is a critique, first, of the Platonic Ideas, and secondly, of the Eleatic doctrine of Being. Neither are absolutely denied. But certain difficulties and consequences are shown in the assumption of either, which prove that the Platonic as well as the Eleatic doctrine must be remodelled. The negation and contradiction which are involved in the conception of the One and Many are preliminary to their final adjustment. The Platonic Ideas are tested by the interrogative method of Socrates; the Eleatic One or Being is tried by the severer and perhaps impossible method of hypothetical consequences, negative and affirmative. In the latter we have an example of the Zenonian or Megarian dialectic, which proceeded, not 'by assailing premises, but conclusions'; this is worked out and improved by Plato. When primary abstractions are used in every conceivable sense, any or every conclusion may be deduced from them. The words 'one,' 'other,' 'being,' 'like,' 'same,' 'whole,' and their opposites, have slightly different meanings, as they are applied to objects of thought or objects of sense--to number, time, place, and to the higher ideas of the reason;--and out of their different meanings this 'feast' of contradictions 'has been provided.' ... The Parmenides of Plato belongs to a stage of philosophy which has passed away. At first we read it with a purely antiquarian or historical interest; and with difficulty throw ourselves back into a state of the human mind in which Unity and Being occupied the attention of philosophers. We admire the precision of the language, in which, as in some curious puzzle, each word is exactly fitted into every other, and long trains of argument are carried out with a sort of geometrical accuracy. We doubt whether any abstract notion could stand the searching cross-examination of Parmenides; and may at last perhaps arrive at the conclusion that Plato has been using an imaginary method to work out an unmeaning conclusion. But the truth is, that he is carrying on a process which is not either useless or unnecessary in any age of philosophy. We fail to understand him, because we do not realize that the questions which he is discussing could have had any value or importance. We suppose them to be like the speculations of some of the Schoolmen, which end in nothing. But in truth he is trying to get rid of the stumbling-blocks of thought which beset his contemporaries. Seeing that the Megarians and Cynics were making knowledge impossible, he takes their 'catch-words' and analyzes them from every conceivable point of view. He is criticizing the simplest and most general of our ideas, in which, as they are the most comprehensive, the danger of error is the most serious; for, if they remain unexamined, as in a mathematical demonstration, all that flows from them is affected, and the error pervades knowledge far and wide. In the beginning of philosophy this