PROFESSOR TYNDALL'S ADDRESS.

Thames Star, Volume VII, Issue 1942, 25 March 1875, Page 4

PROFESSOR TYNDALL'S ADDRESS.

Address delivered before the British Associaiionj assembled at Belfast, tvith additions, ly John Tyndall, F. 8.5., President. London: I ohgmans, Green, and Co., 1874 [COHTIMTJED.] With regard to the influence wielded by Aristotle in the Middle Ages, and which, though to a less extent, he still wields, I would ask permission to make one remark. When the human mind has achieved greatness and given evidence of extraordinary power in any domain, there is a tendency to credit it with similar power in all ether domains. Thus theologians have found comfort and assurance in the thought " that Newton dealt with the question of revelation, forgetful of the fact that the very devotion of his powers, through all the best years of his life, to a totally different class of ideas, not to speak of any natural disqualification, tended to render him less instead of more competent to deal with the theological and historic questions. Goethe, starting from his established greatness as a poet, and indeed from his positive discoveries in Natural History, produced a profound impression among tKe painters of Germany when he published his * Farbenlehre,' in which he endeavoured to overthrow Newton's theory of colours. This theory he deemed so obviously absurd that he considered its author a charlatan, and attacked him with a corresponding vehemence of language. In the domain of Natural History Goethe had made really considerable discoveries ; and we have high authority for assuming that, ,had he devoted himself wholly to that side of science, he might have reached in it an eminence comparable with that which he attained as a poet. In sharpness of observation, in the detection of analogies, however apparently remote, in the classification and organization of facts according to the analogies discerned, Goethe possessed extraordinary powers. These elements of scientific inquiry fall in with the discipline of the poet. But, on the other hand, a mind thus richly endowed in the direction of natural history may be almost shorn of endowment as regards the more strictly called physical and mechanical sciences. Goethe was in this condition. He could not formulate distinct mechanical conceptions ; he could not see the force of mechanical reasoning ; and in regions where such reasoning reigns supreme he became a mere ighits faiuus to those who followed him. I have sometimes permitted myself to , compare Aristotle with Goethe, to credit the Stagirite with an almost superhuman power of amassing and systematizing facts, but to consider him fatally defective on that side of the mind in respect to which, incompleteness has been just ascribed to Goethe. Whewell refers the errors of Aristotle, not to a neglect of facts, but to ' a neglect of £he idea appropriate to the facts ; the idt.a of Mechanical cause, which is Force, and the substitution ef vague or inapplicable notions, involving only relations of space or emotions of wonder.' This is doubtless true; but the word ' neglect' implies mere intellectual misdirection, whereas in Aristotle, as in Goethe, it was not, I believe, misdirection; but ,sheer natural incapacity which lay at the root of his mistakes. Asa physicist, Arirtotle displayed what we should consider some of the worst attributes of a modern physical imvestigator —indistinctness of ideas, confusion of mind, and a confident use of language, which led to the delusive notion that he had really mastered his subject, while he had as yet failed to grasp even the elements of it. He put words in the place of things, subject in the place of object. He preached Induction without practising it, inverting the true order of inquiry by passing from the general to the particular, instead of from the particular tb the general. He made of the) universe a closed sphere, in the centre of which he fixed the earth, proving from general principles, to his own satisfaction and to that of the world for near 2,000 years, that no other universe was possible. His notions of motion were entirely unphysical. It was natural or unnatural, better or worse, calm or violent^no real mechanical conception regarding it lying at the bottom of his mind; He affirmed that a vacuum could not exist, and proved that if it did exist motion in it would be impossible. He determined a priori how many species of animals must exist, and shows on general principles why animals must have such and such parts. When an eminent contemporary philosopher, who is far removed from errors of this kind; remembers these abuses of the a priori method, he will be able to make allowance for the jealousy of physicists as to the acceptance of so-called a priori truths, Aristotle's error 3of detail, as shown by Eucken and Lange, were grave and numerous. He affirmed that only in man we had the beating of the heart, that the left side of the body was colder than the right, that men have more teeth than women, and that there is an empty space at the back of every man's head. There is one essential .quality in physical conceptions which was entirely wanting in those of Aristotle, and his followers. I wish it could be expressed by a word untainted by its associations ; it signifies a capability of being placed as a coherent picture before the mind. Tha Germans express the act of picturing by the word vorstellen, and the picture they call a Vorstellung. We have no word in English which comes nearer to our "requirements than Imagination, and, taken with its proper limitations, the word answers very well; but, as just intimated, it is! tainted by its associations, and therefore objectionable to'some minds. Compare, with reference to.this capacity of mertal presentation, the case of the^ Aristotelian who refers the ascent of water in a pump to Nature's abhorrence of a vacuum, with that of Pascal when he proposed to solve

the question of atmospheric pressure by the ascent of the Puy de Dome. In the one case the terms of the explanation refuse to fall into place as a physical image; in the other the image is distinct^the fall and rise of the barometer being clearly figured as the balancing of two varying and opposing pressures. During the drought of the Middle Ages in Christendom, the Arabian!intellect, as forcibly shown by Draper, was active. With the intrusion of the Moors into Spain, he says, order, learning, and refinement took the place of their x>pposites. When smitten with disease, the Christian peasant resorted to a shrine, the Moorish one to an instructed physician. The Arabs encouraged translations from the Greek philosophers, but not from the Greek poets. They turned in disgust ' from the lewdness -of .our classical mythology, and denounced as an unpardonable blasphemy all connexion between" the impure Olympian Jove and the Most High God.' Draper traces still further than Whewell tbe Arab elements in our scientific terms, and points out that the under garment of ladies retains to this hour its Arab name. He gives examples of what Arabian men of science accomplished, dwelling particularly on Alhazen, who was the first to correct the Platonic notion that rays of light are emitted by the eye. He discovered atmospheric refraction, and points out that we see the sun and the moon after they h*ve set. He explains the enlargement of the sun and. moon, and the shortening of the vertical diameters of both these bodies, when near the horizon. He is aware that the atmosphere decreases in density with increase, of elevationjand actually fixes its height at 58£ miles. In the Book of the Balance Wisdom, besets forth the connexion between the weight of the atmosphere and its increasing density. He shows that a body will weigh differently in a rare and dense atmosphere: he considers the force with which plunged bodies rise through heavier media. He understands the doctrine of the centre of gravity, and applies it to the investigation of balances and steelyards. He recognises gravity is a force, though he falls into the error of making it diminish simply as the distance increased, and of making it purely terrestrial. He knows the relations between the velocities, spaces, and times of falling bodies, and has distinct ideas of capillary attraction. He improved the hydrometer. The determination of the densities of bodies as given by Alhazen approach Very closely to our own. ' I join,' says Draper, in the pious prayer of Alhazen, ' that in the day of judgment the All-Merciful will take pity on the soul of Abur-Raihan, because he was the first of the race of men to construct a table of specific gravities.' If all this be historic truth (and I have entire confidence in Dr Draper), well may he * deplore the systematic manner in which the literature of Europe has contrived to put out of sight our scientific obligations to the Mahommedans.' (1) , The strain upon the mind during the stationary period towards ultra-terrestrial things, to the neglect of problems close at hand, was sure to provoke reaction. But the reaction was gradual; for the ground was dangerous, a power being at hand competent to crush the critic ..who went too far. To elude this power and still allow opportunity for the expression of opinion the doctrine of ' twofold truth' was invented, according to which an opinion might be held ' theologically' and the opposite opinion 'philosophically.' (2) Thus in the thirteenth century the creation of the world in six days, and the uncbangeableness of the individual soul which had been so distinctly affirmed by St. Thomas Aquinas, were both denied philosophically, but admitted to be true as articles of the Catholic faith. When Protagoras uttered the maxim which brought upon him {so' much, vituperation,that 'opposite assertions are equally true,' he simply meant that human beings differed so much from each other that what was subjectively true to the one might be subjectively untrue to the other. The great Sophist never meant to play fast and loose with the truth by saying that one of two opposite assertions, made by the same individual could possibly escape*being a lie. It was not * sophistry,' but the dread of theologic vengeance that generated this double dealing with conviction ; aad it is astonishing to. notice what lengths were possible to men who were adroit in the use of artifices of this kind.

Towards the close of the stationary period, a word-weariness, if I may so express it, took more and more possession of men's minds. Christendom had- become sick of the School philosophy and its verbal wastes, which led to no issue, but left the intellect in everlasting haze. Here and there was heard the voice of one impatiently crying in the wilderlaess, * Not unto Aristotle, not unto subtle hypothesis, not unto church, Bible, or blind tradition, must we turn for a knowledge of the universe, but to the direct investigation of; Nature b^ observation and experiment.* In 1543 the epochmaking work of Copernicus on the paths of the heavenly bodies appeared! The total crash of Aristotle's closed universe with the earth at its centre followed as a consequence, arid ' the earth moves !' became a kind of watchword among intellectual freemen. Copernicus was Canon of the Church of Frauenburg, in the diocese of Ermelarid. 1W three-and-thirty years he had withdrawn himself from the world and devoted himself to the consolidation of his great scheme of the solar system. He made its blocks eternal; and even to those who feared it ; and # desired its overthrow it was so obviously strong that they refrained for a time from meddling with it. In the last year of the life of Copernicus his book appeared : it is said 1 that the old man

(I) Intellectual Development of Europe, p 35ft

received a copy of it a few days before his death, and then departed in peace.

The Italian philosopher Giordano Bruno was one of the earliest converts to the new astronomy. Taking Lucretius as his exemplar, he revived the notion of the infinity of worlds; and, combining \ with it the doctrine of Copernicus, reached the sublime generalization that the fixed stars are suns, scattered numberless through space and accompanied by satellites, which bear the same relation to them that.our earth does to our sun, or our moon to our earth. This was an expansion of transcendert import; but Bruno came closer than this to our present line of thought. Struck with the problem of the generation and maintenance of organisms, and duly pondering it, he came to the conclusion that Nature in her productions does not imitate the technic of man. Her process is one of unravelling and unfolding. The infinity, of forms under which matter appears were not imposed upon it by an external artificer; by its own intrinsic force and virtue it brings these forms forth. Matter is not the- mere naked, empty capacity which philosophers have pictured her to be, but the universal mother who brings forth all things as the fruit of her own womb. This outspoken man was originally a Dominican monk. He was accused of heresy and had to fly, seeking refuge in Geneva, Paris, England and Germany.! In 1592 he fell into the hands of the Inquisition at Venice. He was imprisoned for many years, tried, degraded, excommunicated*-.: and handed over to the civil power, withfethe request that he should be treated gently and ' without the shedding of blood.' This meant that he was to be burnfc;, and burnt accordingly he was, oil the 16th of February, 1600. To escape a similar fat© Galileo," thirty-three years afterwards, abjured, upon his knees, and with his hand upon the holy gospels*, the .heliocentric doctrine which he knew to be true. After Galileo came Kepler, who from hit German home defied the ]JK>ir«r beyond tbe Alps. He traced out from pre-exist-ing observations the laws of planetary motion. Materials were thus prepared for Newton, who bound those empirical laws together by the principle of gravitation.

(To be continued J