The illustrations of Astronomy to this thought are very large. First of the sciences to assume a perfectly rational form, it presents the eternal type of the unfolding of the speculative spirit of man. This springs, no doubt, from the essentially subjective character of astronomy,—more than all the other sciences a construction of the creative reason. From the initiative of scientific astronomy, when the early Greek geometers referred the apparent diurnal movements to geometrical laws, to the creation of the nebular hypothesis, the logical filiation of the leading astronomical conceptions obeys corresponding tidal movements in humanity. Thus it is that
"through the ages one increasing purpose
runs
And the thoughts of men are widened with the
process of the suns."
It was for reasons the Ptolemaic system so long held its sway. It was for reasons it went, too, when it did, hideous and oppressive nightmare! The celestial revelations of the sixteenth century came as the necessary complement of the new mental firmaments then dawning on the thought of man. The intellectual revolution caused by the discovery of the double motion of our planet was undoubtedly the mightiest that man had ever experienced, and its effect was to change the entire aspect of his speculative and practical activity. What a proof that ideas rule the world! Two hundred and fifty years ago, certain new sidereal conceptions arose in the minds of half a dozen philosophers, (isolated and utterly destitute of political or social influence, powerful only in the possession of a sublime and seminal thought,)—conceptions which, during these two centuries, have succeeded in overthrowing a doctrine as old as the human mind, closely interknit with the entire texture of opinions, authority, politics, and religion, and establishing a theory flatly contradicted by the universal dictates of experience and common sense, and true only to the transcendental and interpretative Reason!
At the advent of Modern Astronomy, the apparition of the German, John Kepler, presents itself. Familiarly associated in general apprehension with that inductive triad known as "Kepler's Laws," which form the foundation of Celestial Geometry, it is much less generally known that he was an august and oracular soul, one of those called Mystics and Transcendentalists, perhaps the greatest genius for analogy that ever lived,—that he led a truly epic life, a hero and helper of men, a divine martyr of humanity.
The labors of Kepler were mathematical, optical, cosmographical, and astronomical,—but chiefly astronomical. Two or three of his principal works are the "Cosmographic Mystery," (Mysterium Cosmographicum,) the "New Astronomy," (Astronomia Nova, seu Physica Caelestis,) and the "Harmonies of the World" (Harmonices Mundi). His whole published works comprise some thirty or forty volumes, while twenty folio volumes of manuscript lie in the Library at St. Petersburg. These Euler, Lexell, and Kraft undertook some years ago to examine and publish, but the result of this examination has never appeared. An elegant complete edition of the works of Kepler is at present being issued at Frankfort, under the editorship of Frisch.[1] It is to be in sixteen volumes, 8vo, two of which are published. For his biography, the chief source is the folio volume of Correspondence, published in 1718, by Hansch,[2] who has prefixed to these letters between Kepler and his contemporaries a Life, in which his German heartiness beats even through the marble encasement of his Latinity.
[Footnote 1: Joannis Kepleri Astronomi Opera Omnia. Edidit CH.
FRISCH.]
[Footnote 2: Epistolae ad Joannem Keplerum scriptae. MICHAEL GOTTLIEB
HANSCHIUS. Lipsiae, 1718.]
We have always admired, as a stroke of wit, the way Hansch takes to indicate Kepler's birthplace. Disdaining to use any but mathematical symbols for so great a mathematician, he writes that he was born on the 21st of December, 1571, in longitude 29° 7', latitude 48° 54'! It may be worth mentioning, that on this cryptic spot stood the little town of Weil in the Duchy of Würtemberg. His birth was cast at a time when his parents were reduced to great poverty, and he received very little early schooling. He was, however, sent to Tübingen, and here he pursued the scholastic studies of the age, designing for the Church. But the old eternal creed-questionings arose in his mind. He stumbled at the omnipresence of Christ's body, wrote a Latin poem against it, and, when he had completed his studies, got for a testimonium that he had distinguished himself by his oratorical talents, but was considered unfit to be a fellow-laborer in the Church of Würtemberg. A larger priesthood awaited him.
The astronomical lectureship at the University of Grätz, in Styria, falling vacant, Kepler was in his twenty-third year appointed to fill it. He was, as he tells us, "better furnished with talent than knowledge." But, no doubt, things had conspired to forward him. While at Tübingen, under the mathematician Mästlin, he had eagerly seized all the hints his master threw out of the doctrines of Copernicus, integrating them with interior authorities of his own. "The motion of the earth, which Copernicus had proved by mathematical reasons, I wanted to prove by physical, or, if you prefer it, metaphysical reasons." So he wrote in his "Prodromus Dissertationum Cosmographicarum," which he published two years after going to Grätz, that is, in his twenty-fifth year. In this book his fiery and mystical spirit first found expression, flaming forth in meteoric coruscations. The problem which Kepler attempted to solve in the "Prodromus" was no less than the determination of the harmonic relations of the distances of the planets, which it was given him to solve more than twenty years afterwards. The hypothesis which he adopted proved utterly fallacious; but his primal intuition, that numerical and geometric relations connect the velocities, periods, and distances of the planets, was none the less fruitful and sublime.
Of the facts of Kepler's external life, we may simply say, for the sake of readier apprehension, that, after remaining six years at Grätz, he, in 1600, on the invitation of Tycho Brahe, Astronomer Royal to Rodolph II. of Germany, removed to Prague and associated himself with Tycho, who shortly afterwards dying, Kepler was appointed in his place. The chief work was the construction of the new astronomical tables called the Rodolphine Tables, and on these he was engaged many years. In this situation he continued till 1613, when he left it to assume a professorship at Linz. Here he remained some years, and the latter part of his life was spent as astrologer to Wallenstein. Kepler is described as small and meagre of person, and he speaks of himself as "troublesome and choleric in politics and domestic matters." He was twice married, and left a wife and numerous children ill-provided for.