which points out weakness in theory or errors in practice, without establishing positive truths. Such negative criticism would indeed be poor enough as an ultimate result, but as a means to attaining any positive knowledge or conviction worthy the name, it can not be valued too highly; and until people are again systematically trained to it there will be few great thinkers, and a low general average of intellect in any but the mathematical and physical departments of speculation. On any other subject no one's opinions deserve the name of knowledge, except so far as he has either had forced upon him by others, or gone through of himself, the same mental process which would have been required of him in carrying on an active controversy with opponents." Mr. Grote, in his admirable work on "Plato and the other Companions of Socrates," has the following passage: "Plato is usually extolled by his admirers as the champion of the Absolute--of unchangeable forms, immutable truth, objective necessity, cogent and binding on every one. He is praised for having refuted Protagoras, who can find no standard beyond the individual recognition and belief of his own mind or that of some one else. There is no doubt that Plato often talks in that strain, but the method followed in his dialogues, and the general principles of methods which he lays down here as well as elsewhere, point to a directly opposite conclusion. Of this the Phædrus is a signal instance. Instead of the extreme of generality, it proclaims the extreme of speciality. The objection which the Socrates of the Phædrus advances against the didactic efficacy of written discourse is founded on the fact that it is the same to all readers--that it takes no cognizance of the differences of individual minds nor of the same mind at different times. Socrates claims for dialectic debate the valuable privilege that it is constant action and reaction between two individual minds--an appeal by the inherent force and actual condition of each to the like elements in the other--an ever-shifting presentation of the same topics, accommodated to the measure of intelligence and cast of emotion in the talkers and at the moment. The individuality of each mind--both questioner and respondent--is here kept in view as the governing condition of the process. No two minds can be approached by the same road or by the same interrogation. The questioner can not advance a step except by the admission of the respondent. Every respondent is the measure to himself. He answers suitably to his own belief; he defends by his own suggestions; he yields to the pressure of contradiction and inconsistency _when he feels them_, and not before. Each dialogist is (to use the Protagorean phrase) the measure to himself of truth and falsehood, according as he himself believes it. Assent or dissent, whichever it may be, springs only from the free working of the individual mind in its actual condition then and there. It is to the