Distinctive methods would develop in Greek science and philosophy as intellectual aims diverged and the objects of inquiry were diversified. The first general result had been a mammoth rational guess, an hypothesis suggested by observation, as to the origin of the world of visible things. That water was the source of all things, or undifferentiated matter, or the moist air through condensation, each of these hypotheses was at least a substitute for mythology, and had behind it some consideration of natural processes.1 These beginners also observed the stars, and reflected upon the mechanics of familiar things. They were geometricians. With them geometry became a chosen province of the mind and a source of rational and constraining principles applying to the movements of the heavens and to all things on the earth. The mathematically reasoning sciences, geometry, astronomy, physics, were to be typically Greek. But the Greeks were also to investigate living organisms closely and even

1 66 Matter, in its modern scientific sense, is a return to the Ionian effort to find in space and time some stuff which composes nature. It has a more refined signification than the early guesses at earth and water by reason of a certain vague association with the Aristotelian idea of substance. Earth, water, air, fire, and matter, and finally ether, are related in direct succession so far as concerns their postulated characters of ultimate substrata of nature. They bear witness to the undying vitality of Greek philosophy in its search for the ultimate entities which are the factors of the fact disclosed in sense-awareness. This search is the origin of science" (A. N. Whitehead, The Concept of Nature, p. 19 (Cambridge, 1920)).

experimentally. Aristotle was one of the supreme zoologists of all time.

Thus Greek science began with consideration of the obvious frame and modes of things. It was an inquiry into the why and how-a very closely related, if dual, inquiry. The why pushes the inquirer one step back; so does the how impel him to look behind the thing or process to some more fully explanatory or unfolding antecedent.

As touching the general problem of the world's origin, the how and why might naturally run into each other. It was here that the Greek mind, pushed back and back, took to considering the rationale of matter and material things. It fell among the thorns of more than one logical dilemma, and was driven to exercise itself on general principles and deductions, hypotheses of the intellect, which should be more irrefragable, more absolute than any conclusion from clashing observations. Thought itself must erect the constraining universal principle or truth, the pattern to which sensible things must conform.

With Heraclitus, with Parmenides and Plato, thought passed behind or beyond observation, and found within itself constructive principles of truth and reality. This going behind physics is metaphysics. The metaphysician or philosopher may be interested in applying his theories to the visible world; but his constructive principles are drawn from thought, rather than observation, and will

mould to their abstract and perfectly functioning patterns all things tangible or visible.1

While Greek natural philosophy was changing to metaphysics, specific provinces of natural inquiry separated themselves out from it, and made manifest their objects and their method. Yet there was to be no definite separation between Greek philosophy and Greek natural science. Greek science was apt to lean against philosophy, and loved to shape its results to the dictates of the philosophic reason. There was a mighty bond between them in the conviction, which they shared, that order and law reigned throughout the world of nature as surely as just and retributive fate reigned in the world of men. The order of nature was as just as the fate which punished human crime. This was the faith of Greek philosophy, of Greek science, and of Greek religion. It held together the world of man and nature and made it one.

II

THE MODERN ERA

MATHEMATICS AND THE PHYSICAL SCIENCES

Because of the characteristics of Greek science

1 of this, two thousand years after Plato, Descartes affords a perfect illustration. His constructive principles were metaphysical, and while he interested himself with physics, he conformed the visible world to the constraining patterns of his a priori thinking. He was a metaphysician or philosopher, if one will use that term, and not a scientist.

and the comparatively limited scope of the Greek scientific achievement, we may draw from modern science ampler and clearer illustration of the freedom and energy of the human mind, reaching after knowledge and power through methodical observation, hypothesis, and experimental testing. Modern science rises, say in the fifteenth and sixteenth centuries, partly from the supports of ancient doctrine, but for the most part from observation. Through new or reinvigorated tests of observation and then experiment, it will criticize and partially reject the old conclusions. It will enlarge its scope and find new provinces. Through more penetrating observation, through rationalized and more probable hypotheses, through a novel mathematics and the enlightenment of ingenious and pertinent experiment, it will advance from knowledge to further knowledge, from conclusion to conclusion, and from strength to strength, gaining the knowledge which is power over that which is known. Constantly it has encountered the opposition of superstition and authoritative false opinion, and also has had to cast off many a darling prepossession of its own. In spite of occasional enlightening reversals, it has steadily enlarged its dominion and established its acceptance among men, and has become masterful in its dictates. Triumph upon triumph seem to await its still youthful energies, though to-day its future, with the future of all our civilization, is threatened by an emboldened and

aggressive ignorance, whose marplot passions may replace the old ecclesiastic intolerance of the free advance of truth.

Besides this sinister portent, the recent progress of science has not been smooth. Physics and mechanics, since the close of the last century, have been passing through a revolution of their own: and the end is not in sight. A multitude of novel facts have come to light, which so far have not been ordered in certain and accepted systems. The axioms and basic conceptions of these two sciences seem shaken; and inasmuch as they are themselves fundamental, and affect, if they do not constitute, the bases of other physical sciences, many fundamental scientific concepts are again called up for re-examination. Probably much that seemed assured thirty years ago will be modified. Yet this stirring of the scientific depths is of good omen, and all the more buoyantly science presses forward in the hope of a broader and surer re-establishment of truth.

Since there will be much to say of the frequent modifications of scientific opinion, it is well always to bear in mind the sure advance of tested knowledge in strong and eager periods of history, among which we certainly may include our own time. The brilliant Greek achievement in science was followed by a lengthy diversion of human interest into other channels. But this in turn was succeeded by the grand expansion of physical inquiry