§ 23.
1. We have now made acquaintance with the purely negative tendency of the teachings of the Sophists, and the destroying influence which they exercised on Philosophy. But their teachings were not without their positive effect on the progress of Philosophy in Greece. This positive service they rendered by provoking a reaction which not only brought about the downfall of their own system but initiated a new progressive movement which carried Philosophy in Greece to its highest stage of development. Out of the reaction against the procedure of the Sophists came the Socratic Philosophy, represented in its three masters, Socrates, Plato, and Aristotle, who have won for themselves undying fame in the history of Philosophy.
2. Anaxagoras had, as we know, carried the Ionic Philosophy to Athens, Parmenides and Zeno had there represented the Eleatie School, while Heraclitus and the Pythagoreans were known at Athens by their writings, or it may be that some of the latter visited the city in person. In this way Athens became the centre in which the various schools of Greek Philosophy were brought into contact, and were enabled to influence one another. A first consequence of this conflux of philosophical doctrines was the breaking up of the several philosophical systems -- a result which we observe in the teaching of the Sophists. But this disaster was soon followed by a new development of philosophic thought. The new movement was favoured by the circumstance that its leaders had before them philosophical systems whose defects and onesidedness they were warned to avoid, and were thereby incited to seek a new point of departure for philosophic inquiry. Athens thus became not only the central seat of Art in Greece, but also the home of Greek Philosophy in the period of its greatest glory.
3. If we inquire what was the new point of departure which Greek Philosophy adopted at this period we shall find that philosophic thought, instead of making external nature the only subject of investigation, turned back upon itself, and proclaimed that self-knowledge, theoretical and practical (ethical), was of more importance for the attainment of truth than the knowledge of Nature. Self-knowledge, the investigation of the moral order, had hitherto been neglected in favour of the study of the physical world; it was now accorded the first place in the estimation of the philosopher. Hereby a purer knowledge of the Divine Nature became attainable. And Attic Philosophy thus rose to a Theology that stands high above the opinions regarding God and things divine offered by the earlier philosophical systems of Greece. Theology now became the centre and the crown of philosophical science.
4. Socrates was the founder of Attic Philosophy, or, better, his labours may be said to have prepared the way for it. He did not aim at constructing a complete system of Philosophy. The instruction, to which he applied himself exclusively, was directed to incite his pupils to a deeper study of things, and to guide them in the right path of investigation. All his pupils did not, however, apprehend rightly the mind of their master; many of them fastened upon some one or other of the special points in his teaching, and devoted themselves to the development of the point so selected. These philosophers are said to have been "imperfectly Socratic." Plato, on the other hand, gave comprehensive development to the principles of his master, and, with his clear idealistic mind, brought to its fullest perfection the germs contained in the instructions of Socrates.{1} Plato was succeeded by his pupil Aristotle, who on many points is at variance with his master. But Socrates by his wonderful acuteness and penetration of mind, his quick power of observation, his vast knowledge, and his methodical procedure, was enabled to build up a system which is worthy to take an independent place by the side of Plato's.
Following the order here indicated,
5. We shall first treat of Socrates and the "imperfectly Socratic Philosophers," and then we shall set forth the Philosophical systems of Plato and Aristotle.
{1} Among the immediate disciples of Socrates we may further mention Aeschines an Athenian, Cebes a Theban, Simon a shoemaker of Athens, Xenophon an Athenian general and writer. The latter wrote a life of Socrates and contributed to the Philosophy of Education the well-known Cyropaedia.