Here, in the Lyceum, Greek philosophy was brought to its most complete expression. Here all the threads of Greek cosmological and anthropological undertakings were finally woven together. Here an adjustment was accomplished between Aristotle’s two great predecessors, Plato and Democritus; and materialistic and idealistic realism crystallized in a theory of development. The great form of Aristotle rises to speak the final word of pure Greek civilization, at a time when the custody of Greece had passed from the hands of the Athenians, the Spartans, the Thebans in succession to the Macedonians. He was the most influential thinker that history had seen. In his formative power upon human thought he has scarcely a peer. Dante called him “the master of those who know.” “In my opinion,” said Cicero, “Aristotle stands almost alone in philosophy.” Eusebius said of him, “Aristotle, nature’s private secretary, dipped his pen in thought.” Goethe remarked, “If now in my quiet days I had youthful faculties at my command, I should devote myself to Greek, in spite of all the difficulties I know. Nature and Aristotle should be my sole study. It is beyond all conception what that man espied, saw, beheld, remarked, observed.” The portrait that we draw of Aristotle is very different from that of Plato. Instead of the deeply poetic temper, the man who sees all things in an ideal unity of infiniteness and vastness, we have before us now the scientist in search of facts, the accurate man of good sense, whose imagination does not soar above the clouds, but at the same time has extraordinary fertility in historical and scientific theoretical explanations. His was a life filled with the love of truth. His learning took up into itself the entire range of human knowledge in such a way as to include its earlier development. And what is more, he showed an equal interest in all departments. Aristotle was more of a scientist than Plato, for the theoretical rather than the ethical interest was fundamental in his work. He is the personification and completion of pure Greek learning. =Biography of Aristotle=, 384–322 B. C. =Brief Chronological Sketch of Aristotle’s Life.= First Period――Aristotle the Student――37 years. 384–347 B. C. 384 Born in Stagira in Macedonia. 367 Entered the Academy. Remained 19 years. 347 Left the Academy upon the death of Plato. Second Period――Aristotle the Traveler――12 years. 347–335 B. C. 347 Went to the courts at Atarneus and Mytilene in Asia Minor. 343 Returned to the court of Macedon at Pella, in response to the summons of King Philip, to teach the young prince Alexander. Remained 4 years. 340 Went from Pella to Stagira to engage in scientific work. Remained 5 years. Third Period――Aristotle the Leader of the Lyceum――13 years. 335–322 B. C.