mographicum in which he set forth a relation between the five regular polyhedra and the distances which then were assumed between the planets and the sun in the Copernican system. The genius of the writer was conspicuously displayed in this book and at once attracted attention. Kepler had already in November 1595 addressed a letter to Reymers, in which he explained the ideas contained in his forthcoming work, but the "Cæsarean mathematician" took no notice of the letter of the unknown young man until June 1597, when he had probably heard the book well spoken of, and wrote to Kepler to ask for a copy.[1] In the mad book which he published in the same year, Reymers inserted Kepler's letter of 1595, at which Tycho did not feel particularly pleased, though he had sense enough to acknowledge that Kepler had merely been civil to a man whom he only knew through his scientific writings. In a letter which Tycho wrote from Wandsbeck on the 1st April 1598, to thank him for a copy of the Prodromus (which Kepler had recently sent with a respectful letter), he expressed himself to that effect. At the same time he gave due praise to the ingenious speculations of Kepler, though he had some doubts as to the numerical data employed, and of course he could not help regretting that the Copernican system was the foundation on which Kepler had built. He expressed, however, the hope that Kepler would yet adopt something similar to the Tychonic system, which made Kepler (who throughout furnished the letter with marginal notes) remark: "Quilibet se amat"[2] Shortly afterwards Tycho
- ↑ Ursus had just published a work on chronology, Chronotheatrum sive Theatrum temporis annorum 4000, of which he sent Kepler a copy with the letter (the full title is given by Hanisch, Epist. ad I. Keplerum, p. 90; it must be an extremely scarce book). Kepler was so little aware of the enmity between Tycho and Ursus that he even asked Ursus to forward a copy of the Prodromus to Tycho (Opera, i. p. 233).
- ↑ Epist. Kepleri, p. 102; Opera, i. p. 43 and p. 219; Kepler's marginal notes, p. 189.
