Without Copernicus there could have been no Kepler, without Kepler no Newton. These three men, in the words of a recent astronomer, belong inseparably together, they support and supplement one another. It might be fittingly asked, after which of these three the celestial system should be named; and were it possible to ask these three men for their opinion in this matter, they would probably all give the answer that has been [pg 202] ascribed to one or the other of them: Not my system, but God's Order. Like Copernicus, so Kepler and Newton were profoundly religious men.
Johann Kepler, born of Protestant parents in Württemberg in 1571, was raised a Lutheran. In 1594 he was appointed professor of mathematics at a school in Graz, and after that he dwelt for the most time in Austria, which country became his second home. From Graz he was called to Prague to be mathematician at the imperial court, and from there to Linz to be professor at the college there. His last years were passed at Sagan and Ratisbon, where he died in 1630. Even after having left Austria he gratefully remembered the clementia austriaca and the favor archiducalis. Kepler's astronomical achievements are known to everybody, especially his laws of the planets. With an untiring spirit of research he combined beautiful traits of character, cheerfulness, kindness, and modesty, but chiefly a profoundly religious mind. However, he was in difficult circumstances as far as his religious life was concerned. Quite early he came in conflict with the religious authorities of his confession, particularly for the reason that they considered Kepler's Copernican views as against the Bible, a fact which the learned astronomer could not see. There were also other differences. The conflict became more and more aggravated. It cannot be denied that the Lutheran Church-authorities proceeded against Kepler with a lack of consideration never shown by Rome against men like Galileo. Kepler was expelled from the Lutheran Church, and despite his efforts to be reinstated the ban was never lifted.
Like Kepler, so was his predecessor at the Catholic court of Prague, the Danish astronomer Tycho Brahe (died 1601), a devout Protestant, but the trials of Kepler were spared him. His erroneous idea that the Copernican system conflicted with Holy Writ kept him from subscribing to it: it led him to devise a system midway between Copernicusand Ptolemy. His religious sentiment is evidenced by a passage from a letter of his, written at his father's death, “Although there are many consolations for me, of a religious nature based on Holy Writ, and of a philosophical kind drawn from the contemplation of the fate of all men and of the inconstancy of everything under the moon, it is a special comfort for me that my father departed so sweetly and piously from this valley of misery to the heavenly eternal home, where, according to St. Paul, we shall find a lasting abode.”
But let us return to Kepler. There is evidence that at various times in his life he wavered between his Lutheran confession and the Catholic faith, but that is as far as he went. He was of the opinion that the fundamental truths of both were in accord, and he would not presume to judge of the differences; he had taken a view-point of his own, from which he could not be made to recede. On the other hand, he was shocked when his fellow-Lutherans in Styria were on two occasions severely dealt with, although he personally had been treated with especial consideration. Otherwise his opinions on Catholic matters and the “wisdom” of the Catholic Church were eminently fair; he censured his co-religionists for their invidious attacks on Rome, and for their hesitancy in adopting the Gregorian reform of the calendar. He had friendly relation with many a Catholic scientist, was in correspondence with many Jesuits, was even frequently their guest, receiving stimulus, commendation, and scientific communications from them.
To Kepler the study of astronomy became largely a prayer; the finest of his scientific works he was wont to conclude with the doxology of the Psalmist, “Great is our Lord, and great is His power, and of His wisdom there is no number: praise Him ye Heavens; praise ye Him, O Sun, and Moon, ye Stars and light, and praise Him in your language. Thou, too, praise Him, O soul of mine, thy Lord, thy Creator, as long as it is granted to thee” (Harmonices Mundi, v. 9). His name and work is commemorated in the Keplerbund in Germany, which aims at the promotion of scientific knowledge in the sense of Kepler, in opposition to the misuse of natural science for purposes of materialism and atheism.
The work, begun so happily by Copernicus and Kepler, was completed by the great Englishman, Newton (died 1727). It was he who in his immortal work, Philosophiae naturalis principia mathematica, laid bare the law of the universe, which compels the heavenly bodies to revolve about one another. Therewith the laws of Kepler, and consequently the Copernican hypothesis, became established. When, in 1727, this scientist, at the age of eighty-five, died, his mortal remains were entombed in Westminster Abbey, the Pantheon of the British nation. Lofty [pg 204] science and the reverent worship of his Creator were combined in the noble mind of this great Briton. In an appendix to his master-work, referred to above, he cited his proofs for the existence of God, and stated that “the entire order, as to space and time of all things existing, must have necessarily proceeded from the conception and will of an existing Being,” that “the admirable arrangement of sun, planets, and comets could only emanate from the decree and the design of an All-wise and Omnipotent Being,” that “we admire Him for His perfections, we adore and worship Him as the ruler of the world, we, the servants of the great Sovereign of the Universe.” According to Voltaire, it was stated by Newton's disciple, Clarke, that his master invariably pronounced the name of God with reverent attitude and expression.
Inseparably connected with the history of the Copernican system there is the name, which recalls harsh accusations and painful memories, the name of Galileo. That he had nothing in common with the aims of those who have broken with faith and Christianity, nor with that hostility against his Church for which his name is so often misused, has been made evident by what we have said on another page (see page 189). Not only during his early life was his religious turn of mind evidenced, but also later on and up to the end of his life he continued to observe faithfully the duties of his religion.
One of the greatest physicists of recent times was Christian Huygens, who died in 1695 at his native city, The Hague. To him we owe the epoch-making discovery of the undulation of light, while Newton had held light to be a matter of emission. But while Huygens advanced over Newton in this respect, he paid tribute to human limitation by remaining prejudiced against Newton's theory of gravitation, which he rejected. Huygens was a believing Christian.
In his philosophic dissertation “Kosmotheoros,” a posthumous work, he says in regard to the possibility of the celestial bodies being inhabited: “How could the investigator look up to God, the Creator of all these great worlds, otherwise but in the spirit of deepest reverence? Here it will be possible for us to find manifold proofs to demonstrate His providence and wonderful wisdom; likewise will our contemplation contend against those who are spreading false opinions, such as attributing the origin of the earth to the accidental union of atoms, or of the earth being without a beginning and without a creator.”
Religious fervour is still more pronounced in Huygens' contemporary, Robert Boyle (died 1692), a son of Ireland. While he had made considerable achievements in physics, his chief fame lies in chemistry: he inaugurated the period in which chemistry became gradually an independent science. Although working in a different field of research, he is similar to Newton in many respects: like Newton and Huygens, his love of scientific studies induced him to remain unmarried, like Newton he found his last resting place in Westminster Abbey, but chiefly he is like Newton because of his pious, religious mind. He was much occupied with theological studies, and in them the demonstration from nature of the existence of God, and the author's reverence for the Scriptures are most conspicuous: “In relation to the Bible,” he writes, “all the books of men, even the most learned, are like the planets that receive their light and brightness from the sun.” On his deathbed he made a foundation for apologetic lectures: the Boyle-lectures are held to this very day.