ANCIENT PREFACE TO THE READER.

PROPOSED here, Reader, is my intent to demonstrate in this little book that the Creator, the Best and Greatest, in the creation of this moving world and the arrangement of the heavens, had regard for those five regular bodies These are the "Platonic Solids": the tetrahedron, cube, octahedron, dodecahedron, and icosahedron. Kepler believed the orbits of the planets were nested within these shapes. so celebrated from the time of Pythagoras and Plato down to our own, and that He accommodated the number of the heavens, their proportions, and the system of their motions to the nature of those bodies. But before I allow you to come to the matter itself, I shall discuss some things with you regarding the occasion of this book and the reason for my undertaking, which I have judged to pertain both to your understanding and to my own reputation.

Six years ago, while I was studying at Tübingen under the most celebrated Master Michael Maestlin A significant astronomer who was one of the first to teach the Copernican system in a university setting., I was so disturbed by the many inconveniences of the common opinion concerning the world The "common opinion" refers to the Geocentric or Ptolemaic system, which placed the Earth at the center. that I became greatly delighted with Copernicus, whom Maestlin mentioned very frequently in his lectures. Thus, I not only often defended his views in the physical disputes of the candidates, but I even wrote a careful (2) disputation on the "primary motion," arguing that it happens because of the rotation of the Earth. I was already at the point where I was ready to ascribe the Solar motion to the Earth itself (3)—just as Copernicus did for Mathematical reasons, so I did for Physical, or if you prefer, Metaphysical reasons. Toward this end, I began to collect, partly from the lips of Maestlin and partly by my own effort original: "meo Marte"; literally "by my own Mars," a Latin idiom meaning by one's own labor or strength, the advantages that Copernicus has in Mathematics over Ptolemy. Joachim Rheticus could have easily freed me from this labor, as he followed these points individually, briefly, and clearly in his First Account The Narratio Prima, the first published summary of Copernican theory.. Meanwhile, while I was "rolling that stone" An allusion to the myth of Sisyphus, implying a difficult or repetitive labor., but as a secondary task original: παρεργως (parergōs) alongside my Theology studies, it happened conveniently that I came to Graz and succeeded the late Georg Stadius; there, the nature of my office bound me more closely to these studies. In that place, while explaining the principles of Astronomy, everything I had previously heard from Maestlin or had pursued myself proved to be of great use to me. And just as in Virgil, "Rumor thrives on motion and acquires strength as it goes," so the diligent contemplation of these matters became the cause for further contemplation. Finally, in the year 1595, when I desired to spend my leisure time from lectures well and in accordance with my professional duty, I threw myself into this subject with the full force of my mind.

And there were three things in particular whose causes—why they were so and not otherwise—I persistently sought: the Number, the Size, and the Motion of the Orbs. What emboldened me to dare this was that beautiful harmony of stationary things—the Sun, the fixed stars, and the space between—with God the Father, the Son, and the Holy Spirit (4); a resemblance Kepler famously compared the universe to the Trinity: the Sun representing the Father, the sphere of fixed stars the Son, and the intervening space the Holy Spirit. which I shall pursue further in the Cosmography. Since the stationary things were thus arranged, I did not doubt that the moving things would likewise reveal themselves. Initially, I attacked the matter with numbers, and I considered whether one orb was double, triple, quadruple, or whatever else compared to another; and how much each differed from the next in the Copernican system. I wasted a great deal of time in that labor, as if at play, since no equality appeared either in the proportions themselves or in the increments. I perceived no benefit from it, other than that I engraved the distances themselves, as they were produced by Copernicus, very deeply into my memory. This mention of my various attempts may toss your assent, Reader, back and forth anxiously like the waves of the sea; but being thus fatigued, you may finally retreat all the more gladly to the causes explained in this book, as if to a safe harbor. Nevertheless, I was comforted from time to time and raised to better hope, both by other reasons that follow below and by the fact that motion always seemed to follow distance; where there was a large gap between the orbs, there was also a large gap between the motions. I thought that if God adapted the motions to the prescription of the distances for the orbs, He surely also accommodated the distances themselves to the prescription of something else.

Since I was not succeeding in this way, I tried another approach with a wonderful boldness. (5) I interposed a new Planet between Jupiter and Mars, and likewise another between Venus and Mercury, which two we perhaps do not see because of their smallness, and I assigned them their own periodic original: περιοδικα (periodika) times. For I thought that in this way I would produce some equality of proportions, which proportions would be decreased in order toward the Sun and increased toward the fixed stars: for instance, the Earth is closer to Venus in the size of the terrestrial orb than Mars is...