Chapter II

Our modern idea that science embraces all kinds of knowledge is, as I have mentioned before, a curious reversion to the Greeks. In spite of the fact that they formulated the great deductive laws of physics, such as cause and effect, conservation of matter, etc., and developed an extraordinarily fruitful science of geometry, they remained indifferent to the experimental method. They developed almost no apparatus for experimentation, established no standards of measurement, and their arithmetical symbols were so awkward that only the simplest calculations could be made. They never succeeded in disentangling subjective and objective ideas. Plato could anticipate the modern conception of natural law in his aphorism that God geometrises, but at the same time he vaguely identified the human soul with the stars and endued the universe with life. Democritus pictured the world as an aggregation of atoms, differing only in size, shape, and motion; yet he also tacitly ascribed to them a will or desire to move which was only less pronounced than in those finer particles which constituted the souls of men. Also the four classic elements,--earth, water, air, and fire,--which combined in different proportions to form all material bodies, were actuated by the animistic principle that each element sought its own place. One could multiply these examples of classical thought which confused mechanical forces with the vital attributes of will and desire.

The failure of the Greeks to develop an objective and experimental method was intensified by the domination of the Christian religion during the Middle Ages. The emphasis of thought was placed on the problems of human character. At a time when men were taught that our environment was a trap set by the powers of evil to allure our souls to eternal damnation, there could be little stimulus to study the laws of nature or to apply them to increase our interest in a temporal life. It is customary for historians to condemn the Church for having crushed science, but no concerted opposition was necessary in a society which saw no advantage in gathering its fruits. It was an axiom that truth was the direct consequence of intuition and revelation, that God had revealed in the Bible, and through His living Church, all the knowledge necessary for man’s guidance in a transitory state. To neglect such a certainty for the perceptions of our fallible and sinful senses, and to construct a world from them according to our reason, would be to fall into the sin of the pride of the intellect. Furthermore, in a society small in numbers and in area, where the greater number were believed to have been created to minister to the comfort of the few, little need was felt for mechanical power and industry. The only science which seemed to be worth cultivating was one which was believed to foretell human events and to affect our spiritual life.

It had been generally accepted from ancient times that the stars influenced our lives and foretold the future. Such knowledge was eagerly sought by a society which was principally concerned with religion and was, at the same time, a prey to superstitious fear. It is not surprising that astrology was seriously cultivated. If we grant the postulate that the stars do affect us, then we must admit that astrology was a true science. The positions and the motions of the planets and stars were observed and recorded as accurately as possible, and deductions were made according to rules and laws believed to have been verified by experience. Nor does it seem to me much more credulous to believe that our character is determined by the relative positions of the planets, than to assume, as do Mr. Watson and the modern behaviourists, that our thoughts are caused by the relative positions and motions of the material atoms which happen to compose the substance of our brains. The astrologists had, at least, the great advantage of dealing with real bodies which we can observe, while these psychologists have for their use only the hypothetical and machine-made atoms of the chemist which they can never hope to observe. There is little to choose between the superstition that the planets foretell our characters and the superstition that atoms constitute thought; both lead to equally foolish and irrational practices. And there is the less excuse for the psychologist, since he has had the benefit of a longer past experience than had the astrologer to convince him of the futility of identifying mind and matter.

The only other science which aroused popular interest was alchemy. The basis of this subject was the postulate that all matter was composed of the four elements combined in various proportions. By the use of chemical reagents, the combinations of these elements could be altered and a given substance be thus changed into another. Alchemy is generally associated with the attempt to transmute metals and, in particular, to change lead into gold, because the natural cupidity of their patrons made it advisable for the alchemists to hold that prospect before them in order to obtain a livelihood. In principle, alchemy is but little different from modern chemistry. Our most recent theory still holds that the difference between lead and gold is due only to the numerical relations of a single element, the electron. The difference between chemistry and alchemy does not lie in either their fundamental hypotheses or their methods, but in our vastly superior technique of experimentation and accumulated knowledge. The nature of the modern electronic atom is essentially as fictitious as was the nature of the mediæval elements.

Besides exciting the hope of wealth, alchemy was important as an aid to health and longevity. Since health required that the four elements of the body should be preserved in their proper balance, illness, and even death, were but the temporary or permanent loss of their right proportions. Alchemists, convinced of this truth, were led to seek for a sovereign substance, the philosopher’s stone, which would have the power to restore this disturbed balance and give to its fortunate owner permanent health and life.

It is a mistake to suppose that the Church oppressed these sciences--many of its most orthodox fathers and saints eagerly studied them. The abuses due to the rampant charlatanry of many of their practitioners were repressed, but their serious doctrines were fused into the religion of the time much as, in our day, the clergy have tried to harmonise Christianity and biological evolution. In fact, as we shall see, the most determined opposition which the new Copernican theory of the solar system had to overcome was the fusion of Christian dogma with Aristotelian astrology and alchemy.

It was natural that the first fruits of the new science of the Renaissance should have been in astronomy and mechanics. The accumulated observations of the astrologers had vastly increased the complexity of the Ptolemaic system, and the discrepancies between the observed and calculated positions of the planets had become glaringly evident. When the great treatise of Copernicus was finally published as he lay on his death-bed, it is altogether probable that no one suspected that it marked the beginning of a new philosophy. He had merely proved that the calculations of astronomers were greatly simplified by assuming that the sun, instead of the earth, was the fixed centre of the solar system, and that the earth and other planets revolved about it in circular orbits. It must remain a mooted question whether Copernicus believed that his discovery was only a mathematical device; his book states explicitly that he, as a Catholic, still subscribed to the belief that the earth was actually the fixed centre of the universe as the Church and the Aristotelians both taught to be a necessary article of faith. At all events, it was not until Galileo some sixty years later invented the telescope and turned it on the heavens, that men saw the significance of the discovery. The eye of the telescope penetrated the depths of the solar system. It proved that the planets were not pure celestial matter but were mere masses like the earth. Their brilliance was not a divine fire but ordinary sunlight reflected from their dull surfaces; they, like the earth, were inanimate bodies revolving about the sun and the Copernican system became a fact instead of a mathematic device. It is not extravagant to assert that, with the acceptance of Copernican astronomy, the whole mediæval conception of nature gave place to a reliance on experimental evidence.

The work of Galileo in founding the science of mechanics was fatal to the mysticism of the contemporary alchemists. Instead of the elements with their natural places, their likes and dislikes, their hierarchy of nobility, and their subserviency to planetary influences, he laid down the universal principle that all natural actions were due to mechanical forces whose only function was to alter the motions of bodies and whose amount was measurable in mathematical symbols. His significant work for us was an uncompromising war waged against the scientific dogmatism of the Aristotelians on the clear-cut issue that knowledge of the objective world could be obtained only by experimental evidence, and not by subjective preconceptions. Understood rightly, he had reinstated the Platonic dualism of two worlds, one of matter, and the other of the mind or spirit.

It is significant that during Galileo’s lifetime, so swift was the movement, Descartes saw the trend of the new science and its inevitable effect on philosophy and religion. In his _Système du Monde_, he pictured a universe of matter and motion and nothing else,--a machine. From matter he tried to strip every sensible attribute except extension, or its mere geometrical position and extent. All phenomena became for him merely phases of motion. With the courage of his conviction, he even tried to imagine plants and animals to be mechanically acting automata. One thing only he could not include in this mechanism,--and that was _thought and consciousness_.

The cosmogony of Descartes has long since crumbled to dust, but the gap he made between the subjective and objective worlds has never been closed in spite of incessant later attempts. And these early creators of science, as something distinct from humanism, were quite conscious that they were engaged in a revolution which could end only with the overthrow of the dogmatic science of the Middle Ages, sheltered by the authority of Aristotle and the Bible. Galileo, Descartes, Pascal, and Bacon all declared explicitly that the old order must pass. From their day to ours, we have more and more regarded the universe as a machine, a combination of inert matter and moving forces, acting not as we may desire, but according to invariable laws which we have personified as Nature. Man was left, by the physicists, as a unique outsider who could interpret this machine in terms of his sensations and mind, but could neither alter nor avoid its fateful operation.

Only one step further was needed to identify all science with mechanics and to compress the scientific method within the limits imposed by mechanical laws. This fundamental principle was Newton’s discovery of the universal attraction of matter. According to this law, a single kind of force, depending only on the amount of matter and the distance between bodies, operated to hold the stars in their paths and to cause all the chemical and physical activities of atoms. With its discovery, the mechanistic theory was complete and dominant, and science had, in principle, gone as far as it can ever go. But, what is even more important, Newton grasped in his early years the fact that the scientific method is limited to the experimental investigation of objective phenomena, those which can be classified, measured geometrically, and formulated in laws which predict future events. He held with absolute consistency and restraint that what is once accomplished by this method is permanent. The experimental laws of gravitation, of the pressure of gases, and all others of like nature, are true within the limits of accuracy of our observation and measurement. If these improve, such laws do not fail, their mathematical expression is merely made more precise. They belong to the permanent acquisitions of the mind.