Evening Post. SATURDAY, DECEMBER 27,1930. GREATER THAN NEWTON?

The eight men whom, in cpnlrast with Napoleon and other makers of empires, Mr. Bernard Shaw in his speech at the Einstein banquet described as makers of universes were Pylhogoras, Aristotle, Ptolemy, Copernicus, Galileo, Kepler, Newton, and Einslein —three Greeks, one Pole, one Italian, one German, one Englishman, and one Jew. If Copernicus can be classed as a Prussian and not a Pole, and Einstein as a German as well as a Jew, then Germany and ancient Greece must be credited with three each against two for the rest of the world. But without any "ifs," it is astonishing to find that a century ago the one indubitable German on the list was put by an English philosopher far above all the others, at any rate among the moderns, Galileo was a Greek genius, said Coleridge, and so was Newton; but it would take two or three Galileos and Newtons to make one Kepler. It is in the order of Providence that the inventive, generative, constitutive mind—the Kepler—should come first; and then that the patient and collective mind—the Newton —■ should follow, and elaborate the pregnant queries and illumining guesses of the former. The laws of the planetary system are, in faclv due to Kepler. We praise Newton's clearness and steadiness. He was clear and steady, no doubt, whilst working out, by the help of an admirable geometry, the idea brought forth by another. We cite the opinion of Coleridge, not as representing the verdict of modern science—for Coleridge -was a poet and philosopher and dreamer rather than a man of science—but as a salutary corrective to the lazy notion that the man whose work has been superseded by another's is therefore his inferior in genius and a less conspicuous benefactor of the race. Even Coleridge would not have said of Kepler what Pope said of Newton: Nature, ;uirl Nature's Jaws, Jay hid in night; God said, "Let Newton be!" and all was light. It was at the best but in a sort of twilight that Kepler left the laws of the solar system. In view of the strange association of guesses and fancies and superstitions with the rigidity of Kepler's mathematics we might even say that he left those laws in that kind of "wizard twilight" which Sir William Watson has noted as characteristic of Coleridge's own genius. And since the addition of the latest luminary to Mr. Shaw's constellation we have learnt that there is a catch even in that perfect lucidity with which Nature's laws were supposed to have been revealed by the genius of Newton. If Einstein's theory of relativity has done nothing else for the education of the plain man, it has at least impressed upon him the relativity of human knowledge. But, so far as direct illumination is concerned, he is bound to confess that the speculations and calculations of Einstein have brought to him darkness and not light. In,his bewilderment he is grateful to Mr. J. C. Squire, who, when it was suggested that an epigram on Einstein was needed as a supplement to the epigram in which Pope declared that all was light since Newton's day, wrote as follows: It did not last: the Devil, howling, "Ho!. . Let Einstein "be!" restored the status quo. The tercentenary of Kepler's death was honoured by the "Spectator" on the due dale. (15th November), and having missed that chance we are glad to be reminded of it in time to add our tribute on his birthday. A life which was of unique value to science ran its course, dogged from birth by disease and often by poverty, between the 27th December, 1571, and the 15th November, 1630. Kepler, writes Professor H. Dingle in the "Spectator," more than any of the great men of his epoch (Copernicus, Tycho Brahe, Galileo), harmonised in himself the essential elements of the old and tlio new age. . . Kepler, mystic, philosopher, scientist, artist — what formula can describe the man whoso scientific investigation was religious devotion, to whom observations were sacred, and who would yet refuse to consider a natural interpretation of them if it appeared- inharmonious? It is these limitations, reflecting chiefly to the limitations of the age, but varied by personal obsessions, that make Kepler so profoundly interesting, and instead of inducing some of our scientific Dryasdusts to hold up their hands in holy horror at his ignorance should increase their admiration for the imperishable results that he nevertheless achieved. In an early (realise a speculation which renuired a large increase in the num-

her of the planets, then supposed lo be six, was confronted with the opinion of Rheticus that the number G was sacred, and Kepler'fs answer combined faith and subtlety in a characteristically delightful fashion. The "sacredness " oC Ihe number was, he argued, of much more recent date than the creation of tlie worlds, and could not therefore account for it. The. conflict between traditional authority and sensory evidence as the basis of science, which, as Professor Dingle says, was pre-eminently the question at issue in the early 17th century, was comprehensively dealt with by Kepler as follows:— Now as touching the, opinions of-the Saints about these natural points. I answer in one word, That in Theology the weight of Authority, but in Philosophy the weight of Reason, is to bo considered. Therefore Sacred was Lactontius, who denyed the Earth's rotundity; Sacred was Augustine, who granted the Earth to be round, but denyed the Antipodes; Sacred is the Liturgy of our Moderns, who admit the smallness of the Earth, but deny its Motion: But to me more Sacred than all these is Truth, who, with respect to the Doctors of the Church, do demonstrate from Philosophy that the Earth is both round, cireumhabited by Antipodes, of a most contemptible smallnessn, and, in a word, tha( it is ranked amongst the Planets. "Who else," asks Professor Dingle, "could give us such a reconciliation as this?" We certainly cannot answer the question, but here Kepler's "reconciliation" concedes so little to the established faith, and throughout his career he was so fearless in his devotion lo the ideal here proclaimed, that one wonders that it was apparently only one of his works, and that not of the first importance, that was placed upon the Index. Quite early in his studies Kepler had acquired the settled conviction that the actual disposition of the solar system was determined by some abstract reason which it Avas not beyond the power of the human intellect to discover and understand. There were, he says, three things in particular of which I pertinaciously sought the causes 'why they are not other than they are: the number, the size, and the motion of the orbits. The first two of Kepler's great discoveries were announced in the "Commentaries of the Motion of Mars" (1609), in which he proudly claimed to have "led the captive planet to the foot of the Imperial throne." Jn this extraordinary treatise, which is regarded to-day as "one of the greatest works in the history of science," Kepler finds the origin of the tides in the fact that the sphere of the attractive virtue which is in. the moon extends as far as the earth and entices up the waters. He' adds that if the attractive virtue of the moon extends as far as the earth, it follows with greater reason that the attractive virtue of. the earth extends as far as the moon, and much farther. There is really no need to lament the rejection of the slory that Newton discovered the law of gravitation by watching the fall of an, apple. A much simpler explanation is to suppose that he had read Kepler's "Commentaries on the Motion of Mars." It was in the same work that Kepler announced the two discoveries which are now known as his first and second laws, viz., that the planets move in ellipses with the sun in a focus of each, and that they move in these orbits in such a manner that the line joining each to the sun sweeps out equal areas in equal times. The book has accordingly been described as "the intermediate place, the connecting link between the discoveries of Copernicus and those of Newton." A third law was added by Kepler in 1618. The relation of the three laws lo the work of Newton is succinctly stated as follows by Mr. Walter W. Bryant:— It was reserved for Newton to establish the Laws of Motion, to find the law of force that would constrain a planet to obey Kepler's first and second Laws, and to prove that it must therefore also obey the third. We may conclude our article with the striking tribute with, which Professor Dingle brings his "Spectator" to a close:— It is by his unswerving loyalty to Truth that Kepler commands our homage, and not forgetting the daring imagination of Copernicus and the magnificent intellect of Galileo, we feel unable to quarrel with Brewster when he places Kepler next to Newton in the hierarchy of great men. His three laws of planetary motion have been the guidance of three- centuries of research, and without 'them the great work oE Newton would liavo been, impossible, but it is. the glory of Kepler that the man transcends tho achievement. His work has brought him recognition, but it is he whom primarily we1 recognise.