Plato had, in truth, a conception of science which no knowledge then attained—perhaps one may add, no knowledge ever attainable—could completely satisfy. Even the rigour of mathematical demonstration did not content him, for mathematical truth itself rested on unproved assumptions, as we also, by the way, have lately discovered. Perhaps the Hegelian system would have fulfilled his requirements; perhaps not even that. Moreover, that the new order which he contemplated might be established, it was necessary to begin by making a clean sweep of all existing opinions. With the urbanity of an Athenian, the piety of a disciple, and the instinct of a great dramatic artist, he preferred to assume that this indispensable task had already been done by another. And of all preceding thinkers, who was so well qualified for the undertaking as Socrates? Who else had wielded the weapons of negative dialectic with such consummate dexterity? Who had assumed such a critical attitude towards the beliefs of his contemporaries? Who had been so anxious to find a point of attachment for every new truth in the minds of his interlocutors? Who therefore could, with such plausibility, be put forward in the guise of one who laid claim to no wisdom on his own account? The son of Phaenaretê seemed made to be the Baptist of a Greek Messiah; but Plato, in treating him as such, has drawn a discreet veil over the whole positive side of his predecessor’s teaching, and to discover what this was we must place ourselves under the guidance of Xenophon’s more faithful report. Not that Xenophon is to be taken as a perfectly accurate exponent of the Socratic philosophy. His work, it must be remembered, was primarily intended to vindicate Socrates from a charge of impiety and immoral teaching, not to expound a system which he was perhaps incompetent to appreciate or understand. We are bound to accept everything that he relates; we are bound to include nothing that he does not relate; but we may fairly readjust the proportions of his sketch. It is here that a judicious use of Plato will furnish us with the most valuable assistance. He grasped Socratism in all its parts and developed it in all directions, so that by following back the lines of his system to their origin we shall be put on the proper track and shall know where to look for the suggestions which were destined to be so magnificently worked out.[86] II.