KEPLER, Jonx, a celebrated astronomer, was born at \Viel, in the duchy of Wirtemberg, on the 27th Dec. 1571, and was the son of Henry Kepler, a respectable officer in the army, whom misfortunes had reduced to indigent cir cumstances. Notwithstanding this reverse of fortune, he was desirous to give his son the best education in his pow er ; and though ) oung Kepler was sent to different schools, and placed under different masters, yet his avidity for know ledge was so great, that he made the most rapid proficien cy in his early studies. He was sent in the year 1589 to Tubingen ; and in 1591, he studied mathematics at the uni versity of that city, under the celebrated Mxstiinus, who had, in his early life, made an oration in favour of the Co pernican hypothesis, which is said to have turned the atten tion of Galileo to the true system of the universe. He was first admitted to the degree of bachelor, and afterwards to that of master of philosophy ; and after studying theology, he undertook the duties of the ministry for a short time. His passion for science, however, induced him to withdraw his views from the church, and to devote his whole leisure to his favourite studies. In 1594, lie was invited to Gratz in Styria, to fill the mathematical chair in the university of that city ; and it seems to have been after he accepted of the appointment, that he embodied those speculations re specting the analogies and harmonies of nature, which he published at Tubingen, in 1596, under the title of, Prodro 712 21 3 dissertationum cosnzographicarum. continens mysterium cosnzographicum de udmirabili proportione orbium cwIcstium, deque cauais calorunz numeri. nzagnitudinis, motuunzque pe riodzcorum genuiniks et propriis, demonstratum per quinque regularia corpora geometrica. To this work is added a pa per by Rheticus, on the Copernican system, and another by daestlinus. III order to discover why the planets were six in number, and why the dimensions of their orbits were such as Copernicus had described them, he studied the properties of numbers and plane figures with success. It,
however, occurred to him, that while the plane regular figures may be infinite in number, the number of regular solids was limited to five ; and he attempted to discover a relation between their dimensions and the distances of the planetary orbits. A cube, for example, if inserted in the sphere of Saturn, would, he supposed, touch by its six planes the sphere of Jupiter ; and, in like manner, the other icgular solids would determine the intervals of the other orbits. \Vhen Kepler was afterwards asked by Thomas Lansius to which of his own works he gave the preference, he replied, that when he discovered the sublime secret of the five regular bodies, he valued it more than he would have clone the possession of the whole electorate of Saxony.
Kepler sent a copy of his work to the celebrated Tycho Brahe, w ho had been too long familiarised with celestial observations, to place any value on such wild speculations. He wrote to Kepler, and urged him " first to lay a solid foundation for his views by actual observations, and then by ascending from these, to strive to reach the causes of things." This advice, which contains the whole substance of is called the Baconian philosophy, no doubt induced Kepler to renounce these visionary speculations, and thus to lay the foundation of those substantial discoveries, to which he was afterwards conducted.
In the same year on which that work appeared, Kepler ' married a lady of a noble family ; but in the year 1598, he was persecuted for his religious principles, and was driven from Gratz. Ile was, however, recalled by the states of Styria ; hut as he did not think his situation sufficiently se cure against future molestations, he accepted of a very pressing invitation from Tycho to settle in Bohemia, and to assist him in his calculations ; and lie accordingly removed thither with his family and books in the year 1600. Dui ing this journey, he was seized with a quartan ague, which lasted eight months.