Science

Besides studying individual sciences, the Greeks paid even more attention to the laws of thought, and to the examination of the essence of the methods by which knowledge in general is acquired. In opposition to Plato's theory that all knowledge is but the un folding and development of forgotten memories of a previous state of existence, Aristotle taught that we learn to reach the generalizations, which alone the Greeks regarded as knowledge, by remembering, comparing and co-ordinating numerous particular acts or judgments of sense, which are thus used as a means of gaining knowledge by the action of the innate and infallible nous or intellect. Neither Plato nor Aristotle could be satisfied without finding infallibility somewhere. Aristotle, it is true, investigated the logical processes by which we pass from particular instances to general propositions, and laid stress on the importance of observing the facts before generalizing about them, but he had little appreciation of the conditions in which observation and the induction based on it must be conducted in practice in order to obtain results where the probability of error is a minimum. Aristotle regarded induction merely as a necessary preliminary to true science of the deductive type best seen in geometry, and, in applying his principles, he never reached the "positive" stage, in which metaphysical problems are evaded, if not excluded, and a scheme of natural knowledge built up in a consistent manner, so that metaphysical ideas, though they may underlie the founda tion of the ultimate conceptions, do not intrude between the parts of the building. Hence Aristotle's explanations often turn directly on metaphysical ideas such as form, cause, substance, terms which do not occur (in the Arist6telian sense) in modern scientific terminology.

The Origin of Mechanics.

A century later than the time of Aristotle, Archimedes of Syracuse (287 to 212 B.C.) formulated the fundamental conceptions of hydrostatics, and took what may be regarded as the first step in the exact science of mechanics. The use of the lever must have been discovered at a very early date, and Archimedes set to work to study its quantitative laws. He made use of axioms which seemed to him to be simpler, and applied thereto deductive principles learnt from the geometers. Nowadays we should treat the law of the lever of unequal arms as one that is verified by direct and familiar experiment, and use it, in its turn, as the starting point for further deduction. Neverthe less, Archimedes' proof is of use and interest, a true type of all scientific "explanations." It reduces an unfamiliar phenomenon to others already well known to our minds, which, being creatures of habit, regard the familiar cases as in no need of explanation.

The Dark Ages and Mediaeval Period.

Thus before the intellectual activity of Greece was absorbed by the utilitarianism of Rome, which, in its turn, was lost in the dark ages following the barbarian conquests, the seeds were sown which, germinating after the lapse of centuries, developed in the more fruitful soil of the age of experiment. The ancient knowledge only survived frag mentarily in compendiums written just before the dark ages. Thereafter, secular learning, based on those compendiums, settled down into the elementary "trivium," consisting of grammar, rhet oric and dialectic, and the more advanced "quadrivium," music, arithmetic, geometry and astronomy. Music included a half

mystical doctrine of numbers and the rules of plainsong; geom etry consisted of a selection of the propositions of Euclid with out the demonstrations ; while arithmetic and astronomy were cultivated chiefly because they taught the means of finding Easter. Meanwhile, the early alchemists of Alexandria, by the aid of mystical analogies with the conceptions of astrology, were making primitive experiments on the transformations of various substances. It was probably from them that the "sacred science" passed to the Arabs, among whom the greatest was one Jabir, who (c. A.D. 750 discovered many new chemical reactions and compounds.

With the intellectual revival in the west which began in the iith century, and the gradual recovery of some of the lost works of the ancient writers, we turn a new page. The controversy be tween Plato and Aristotle upon the doctrine of ideas fascinated the minds of the middle ages, saturated as they were with the logical subtleties of dialectic. This controversy originated the long debate on the reality of universals, which absorbed the intellectual energies of many generations of men. Did reality belong only to the idea or universal—to the class rather than to the individual— to the common humanity of for instance, rather than to each isolated being? Or were the individuals the reality, and the universals mere names or mental concepts? In this question, trivial as it seems at first sight, logical analysis disclosed to the mediaeval mind the whole theory of the universe. Either answer contained danger to theological orthodoxy as then understood; hence the fervour with which it was debated. But, as communi cation with the East was reopened early in the 13th century, Latin translations of Aristotle's works were recovered gradually ; the whole of Aristotle's philosophy was reimported into the schools of Europe, and reconciled with and adapted to Christian theology chiefly by the work of Saint Thomas Aquinas. A complete rational synthesis of knowledge was thus put together, in which Religion, Philosophy and Science formed inter-connected parts of the whole. In virtue of this synthesis, for three hundred years Aris totle reigned supreme in European thought, and exponents of the scholastic philosophy, ignoring their master's teaching on the need of experiment, settled questions of fact as well as those of opinion by an appeal to his books. Nevertheless, the subtlety of the school men kept alive intellectual interests in Europe, and thus prepared the way for science. Outside the newly founded universities, experiment was carried on by the labours of the alchemists, who, early in the 13th century, borrowed ideas from the Arabs, and began to search for an elixir vitae and for a means of transmuting baser metals into gold. But alchemy never quite squared its ac count with orthodox theology, and the "sacred science" of the Alexandrians became associated in the mediaeval mind with the "black art" of witchcraft. Even a man like Roger Bacon, who, with some astrological mysticism, had a more modern idea of experiment both in chemical and physical problems, did not escape condemnation.