But these main propositions, which the modern scientist regards as his own gains, because he has had to win them afresh by his own toil from the errors of the ancient and mediæval world, are of no great significance when compared with the far greater residuum of questions that still remain unanswered. Du Bois-Raymond, as is well known, described these “world riddles” in the year 1880 as in part unsolved, in part insoluble. They are seven in number: (1) The nature of matter and force; (2) the origin of motion; (3) the first beginning of life; (4) the adaptation of nature to certain ends; (5) the rise of sensation and consciousness; (6) the origin of thought and speech; (7) freedom of will.
It is easy to see that, compared with these fundamental questions, which may be summed up in the great question of all, “God and the world,” the whole sequence of cosmic research from Anaximander to Haeckel is merely of secondary importance. It is, as it were, the surface of the matter; and even if, with Goethe, we feel the inadequacy of the apothegm of Haller, the poet and naturalist, “Into the heart of nature no created spirit may penetrate,” yet we cannot but see that as yet we poor mortals are only nibbling at the rind, and that centuries more of labour are needed to penetrate its diamond hardness.
Thus everything that has hitherto been achieved is, as it were, a mere prelude to the abstract presentment of cosmic principles, and consequently the rudimentary beginnings of study in this sphere are far less remote from its present condition than is the case in any other department of the intellectual activity of mankind. And hence, even at the present day, the consideration of Greek philosophy is not only the most interesting, but also by far the most directly profitable part of the study of antiquity. No man who has not thoroughly studied the systems of Democritus, Plato, and Aristotle can become a profound philosopher in our own time.
“The love of wisdom” was the name which, from the fifth century B.C. onwards, the Greeks bestowed on any kind of intellectual endeavour which was diverted from the practice and directed to the theory of life. The scope of this striving naturally varied in different periods. In the infancy of Greek speculation, i.e., in the sixth and fifth centuries B.C., men pored with wide, childlike eyes over the marvels of nature that lay about them and tried to find in natural science the solution of the riddle of existence. Philosophy was then mainly the embodiment of scientific and mathematical research, that is to say, it was what we nowadays call “Science.”
A troublous period followed, represented by the Sophists, a time of youthful storm and stress, out of which the mature philosophy of ideas developed towards the end of the fifth century. The term “philosopher” begins to acquire a professional meaning. Side by side with the Sophist, who supplied “culture” in return for money, stood the philosopher, who directed the course of education without remuneration. At first, it is true, this education was confined to morals. But in Plato it proceeded to expand into a study that comprised mathematics, logic, physics, and ethics, as well as politics, forming a pyramid built on the broadest of possible bases and culminating in the idea of Good. By that time a “philosopher” had come to mean one who is capable of grasping the eternal idea (Plato, Rep. VI, 484 A). Next, in the Universal Encyclopædia of Aristotle, this platonic structure is completed and made habitable within and fitted to human requirements. Under him the idea and the term “philosopher” attained its maximum extension. Thereafter both begin to narrow down. The end of the fourth century witnessed the collapse of the Greek state, to the insecure structure of which the philosophers had never been blind.
With the fall of the Hellenic municipal system and the rise of the Macedonian sovereignty a new world comes into being, in which the leaders are monarchs and no longer individual citizens. The outlook and sphere of action of the individual is restricted. Men grow to be eminent in practical affairs, experts in the art of living, less eager to solve the riddle of the universe than that of the personal Ego, by withdrawing men from the tumult of external affairs and guiding them into the imperturbable calm of philosophic conviction as into a sure haven. Hence in the systems of the Stoa and of Epicurus and Pyrrho the designation of philosopher assumes the meaning of a counsellor in the conduct of life, who, in the lack of political liberty then prevailing, held up an ideal of liberty within, which no tyrant could menace.
In proportion as the sphere of philosophy in the Hellenistic world narrowed to the consideration of the Useful and the Practicable, the sphere of its influence widened. Alexander’s expedition had thrown the East open to Greek civilisation, and the assiduous and subjective temperament of the youth of the Semitic peoples was drawn to the wisdom of the Greeks. An active process of endosmosis and exosmosis set in between the countries of the West and East. During the period from the third to the first century B.C. this interchange created a new civilisation, destined to form the basis of the Imperium Romanum in matters temporal and the Imperium Christi in matters spiritual. But at this period the clear outlines of development tend to become blurred.
As the Hellenic nation expands into the Hellenistic peoples, as the national language of Greece becomes the common medium of the East, nay, of the whole civilised world, the eclecticism which had been formed out of certain elements of the old Greek philosophy under the dominant influence of the Stoa gained ground on all sides. In the time of Christ, Greek philosophy is an indispensable requisite of the higher culture, and the university of Athens, with its professors, whose appointment the state soon took upon itself, is the one where the educated Roman and Cappadocian alike must have studied. The Greek private tutor, recommended by the head of some school or other at Athens, becomes a standing institution in Roman families of distinction, and is treated with the contempt due to such a Græculus, ranking first among the slaves of the household.