Johann Kepler[159] earned for himself the proud title of "lawmaker for the universe" in defiance of his handicaps of ill-health, family troubles, and straitened finances.[160] Born in Weil, Wurtemberg, (December 27, 1571) of noble but indigent parents, he was a sickly child unable for years to attend school regularly. He finally left the monastery school in Mulifontane in 1586 and entered the university at Tübingen to stay for four and a half years. There he studied philosophy, mathematics, and theology (he was a Lutheran) receiving the degree of Master of Arts in 1591. While at the university he studied under Mæstlin, professor of mathematics and astronomy, and a believer in the Copernican theory. Because of Mæstlin's teaching Kepler developed into a confirmed and enthusiastic adherent to the new doctrine. [Footnote 159: The authoritative biography is the _Vita_ by Frisch in vol. VIII, pp. 668-1028 of _Op. Om. Kep._] [Footnote 160: Frisch: VIII, 718. [Transcriber's Note: Missing footnote reference in original text has been added above in a logical place.]] In 1594 he reluctantly abandoned his favorite study, philosophy, and accepted a professorship in mathematics at Grætz in Styria. Two years later he published his first work: _Prodromus Dissertationum continens mysterium cosmographicum_ etc. (1596) in which he sought to prove that the Creator in arranging the universe had thought of the five regular bodies which can be inscribed in a sphere according to which He had regulated the order, the number and the proportions of the heavens and their movements.[161] The book is important not only because of its novelty, but because it gave the Copernican doctrine public explanation and defense.[162] Kepler himself valued it enough to reprint it with his _Harmonia Mundi_ twenty-five years later. And it won for him appreciative letters from various scientists, notably from Tycho Brahe and Galileo.[163] [Footnote 161: Delambre: _Astr. Mod._ 314-315.] [Footnote 162: Frisch: VIII, 999.] [Footnote 163: Ibid: VIII, 696.] As Kepler, a Lutheran, was having difficulties in Grætz, a Catholic city, he finally accepted Tycho's urgent invitation to come to Prague.[164] He came early in 1600, and after some adjustments had been made between the two,[165] he and his family settled with Tycho that autumn to remain till the latter's death the following November. Kepler himself then held the office of imperial mathematician by appointment for many years thereafter.[166] [Footnote 164: Ibid: VIII, 699-715.] [Footnote 165: Dreyer: 290-309.] [Footnote 166: Frisch: VIII, 715.]