Mysterium Cosmographicum

Abstract

In the preface to his first book, the Mysterium Cosmographicum of 1596,1 Kepler summarized the early investigations leading to that book with admirable precision: “above all there were three things of which I diligently sought the reasons why they were so, and not otherwise: the number, size, and motion of the spheres.” 2 These were novel questions, and indeed the Mysterium was a little book filled with peculiar questions, a book whose purpose was only in part scientific. Kepler poured forth his ideas enthusiastically, and although he was quick to admit their flaws, he was equally quick to excuse them. His exuberance was not yet balanced by the self-criticism which distinguished his mature writings. His technical command of mathematics and astronomy was still insecure. The questions he raised in the Mysterium, for all their originality, had no common themes beyond Copernican cosmology and Kepler’s desire to understand, through it, the mind of the Creator.