The highest problem of Science is the problem of Method. Hitherto man has worked on Nature only piecemeal. The understanding and the logic-faculty are allowed to usurp the rational and creative powers. One would say that scientists systematically shut themselves out of three-fourths of their minds, and the English have been insane on Induction these two hundred years. This unholy divorce has, as it always must do, brought poverty and impotence into the sciences, many of which stand apart, stand haggard and hostile, accumulations of incoherent facts, inhospitable, dead.
It is when contemplated in its historic bearings, as an education of the faculties of man, that the emphasis that has been placed on special scientific methods discloses its significance. The speculative synthesis of Greek and Alexandrine Science was a superb training in Deduction,—in the descent from consciousness to Nature. Abstracted from its relations with reality, the scholasticism of the Middle Ages pushed Deduction to mania and moonshine. Then it was, that, in the sixteenth and seventeenth centuries, the Occidental mind, astir under the oceanic movements of the modern, arose to break the spell of scholasticism that had fettered and frozen the intellect of man. An all-invading spirit of inquiry, analysis, skepticism, became rife. An unappeasable hunger for facts, facts, facts, took possession of the general intellect. It was felt that abstraction was disease, was death,—that speculation had to be vitalized and enriched from experience and experiment. This tendency was inevitable and sublime, no doubt. But it remains for modern times to emulate Nature and carry on analysis and synthesis at once. A great discovery is the birth of the whole soul in its creative activity. Induction becomes fruitful only when married to Deduction. It is those luminous intuitions that light along the path of discovery that give the eye and animus to generalization. Science must be open to influx and new beneficent affections and powers, and so add fleet wings to the mind in its exploration of Nature.
In Kepler was the perfect realization of the highest mission of Method. Powerfully deductive in the structure of his intellect, nourished on the divine bread of Plato and the Mystics, he yet united to these a Baconian breadth of practical power. Years before the publication of the "Novum Organum," he gave, in his "Commentaries on the Motions of Mars," a specimen of the logic of Induction whose circular sweep has never been matched. Prolific in the generation of hypotheses, he was yet remorseless in bringing them to the test of experiment. "Hypotheses which are not founded in Nature please me not," wrote he,—as Newton inscribed "Hypotheses non fingo" on the "Principia." Surely never was such heroic self-denial. Centurial vigils of baffling calculations —(remember, there was then little Algebra, and neither Calculus nor Logarithms)—were sacrificed without a regret except for the time expended, his tireless intellect pressing on to new heights of effort. His first work, the "Mysterium Cosmographicum," is the record of a splendid blunder that cost him five years' toil, and he spent ten years of fruitless and baffled effort in the deduction of the laws of areas and orbital ellipticity.
But this audacious diviner knew well the use of Hypothesis, and he applied it as an instrument of investigation as it had never been applied before. The vast significance of Hypothesis in the theory of Scientific Method has never been recognized. It would be a good piece of psychology to explore the principles of this subtile mental power, and might go far to give us a philosophy of Anticipation. The men of facts, men of the understanding, observers,—as we might suppose,—universally show a disposition to shun theorizing, as opposed to the exactness of demonstrative science. And yet it is quite certain, that, in proportion as one rises to a more liberal apprehension, the immense provisional power of speculative ideas becomes apparent. Laplace asserted that no great discovery was ever made without a great guess; and long before, Plato had intimated of these "sacred suspicions of truth," that descend dawn-like on the mind, sublime premonitions of beautiful gates of laws. It is these launching tentatives which bring phenomena to interior and metaphysical tests and bear the mind swift-winged to Nature. Of course, there are various kinds of conjecture, and its value will depend on the brain from which it departs. But a powerful spirit will justify Hypothesis by the high functions to which he puts it. His guesses are not for nothing. Many and long processes go to them.—The inexhaustible fertility displayed by Kepler is a psychologic marvel. He had that subtile chemistry that turns even failures to account, consumes them in its flaming ascent to new reaches. After years of labor on his theory of Mars, he found it failed in application to latitudes and longitudes "out of opposition." Remorselessly he let his hypothesis go, and drew from his failure an important inference, the first step towards emancipation from the ancient prejudice of uniform, circular motion.
Such a genius for Analogy the world never before saw. The perception of similitude, of correspondence, shot perpetual and prophetic in this man's glances. To him had been opened the subtile secret, key to Nature, that Man and the Universe are built after one pattern, and he had faith to believe that the laws of his mind would unlock the phenomena of the world.
The law of Analogy flows from the inherent harmonies of Nature. Of this wise men have ever been intuitive. The eldest Scriptures express it. It is in the Zend-Avesta, primal Japhetic utterance. It vivified that subtile Egyptian symbolism. The early Greeks and the Mystics of Alexandria knew it. Jamblicus reports of Pythagoras, that "he did not procure for himself a thing of this kind through instruments or the voice, but, by employing a certain inevitable divinity, and which it is difficult to apprehend, he extended his ears and fixed his intellect in the sublime symphonies of the world,—he alone hearing and understanding, as it appears, the universal harmony and consonance of the spheres and the stars that are moved through them, and which produce a fuller and more intense melody than anything effected by mortal sounds."
From the sublime intuitions of the harmonies of Nature and the unity of the Universe unfold the bright doctrines of Series and Degrees, of Correspondence, of Similitude. On these thoughts all wise spirits have fed. Indeed, you can hardly say they were ever absent. They are of those flaming thoughts the soul projects, splendid prophecies that become the light of all our science and all our day. Plato formulated these laws. Two thousand years after him, the cosmic brain of Swedenborg traced their working throughout the universal economies of matter and spirit, and Fourier endeavored to translate them into axioms of a new social organization.
These doctrines were ever present to the mind of Kepler; and to what fruitful account he turned Analogy as a means of inductive speculation his wonderful anatomy of his discoveries reveals. He fed on the harmonies of the universe. He has it, that "harmony is the perfection of relations." The work of his mature intellect was the "Harmonices Mundi," (Harmonies of the World,) in which many of the sublime leadings of Modern Science, as the Correlation of Sounds and Colors, the Significance of Musical Chords, the Undulatory Theory, etc., are prefigured. We must account him one of the chief of those prophetic spirits who, by attempting to give phenomena a necessary root in ideas, have breathed into Science a living soul. The new Transcendental Anatomy,—the doctrine of Homologies,—the Embryologic scheme, revealing that all animate forms are developed after one archetype,—the splendid Nebular guess of Laplace,—the thought of the Metamorphosis of Plants,—the attempts at profounder explanations of Light and Colors,—the rising transcendentalism of Chemistry,—the magnificent intuition of Correspondence, showing a grand unity of design in the nodes of shells, the phyllotaxism of plants, and the serialization of planets,—are all signs of the presence of a spirit that is to usher in a new dispensation of Science, fraught with divinest messages to the head and heart of man.
Kepler regarded Analogy as the soul of Science, and he has made it an instrument of prophecy and power. Thus, he inferred from Analogy that the sun turned on its axis, long before Galileo was able to direct his telescope to the solar spots and so determine this rotation as an actual fact. He anticipated a planet between Mars and Jupiter too small to be seen; and his inference that the obliquity of the ecliptic was decreasing, but would, after a long-continued diminution, stop, and then increase again, afterwards acquired the sanction of demonstration. A like instance of anticipation is afforded in the beautiful experiment of the freely-suspended ball revolving in an ellipse under the combined influence of the central and tangential forces, which Jeremiah Horrocks devised, when pursuing Kepler's theory of planetary motion,—his intuition being, that the motions of the spheres might be represented by terrestrial movements. We may mention the observation which the ill-starred Horrocks makes, in a letter,[1] on the occasion of this experiment, as one of the sublimities of Science:—"It appears to me, however, that I have fallen upon the true theory, and that it admits of being illustrated by natural movements on the surface of the earth; for Nature everywhere acts according to a uniform plan, and the harmony of creation is such that small things constitute a faithful type of greater things." Another instance is afforded in the grand intuition of Oken, who, when rambling in the Hartz Mountains, lit upon the skull of a deer, and saw that the cranium was but an expansion of vertebrae, and that the vertebra is the theoretical archetype of the entire osseous framework,—the foundation of modern Osteology. And still another is the well-known instance of the change in polarization predicted by Fresnel from the mere interpretation of an algebraic symbol. This prophetic insight is very sublime, and opens up new spaces in man.
[Footnote 1: Correspondence, 1637]