1. Kepler , Johannes . 1937. Gesammelte Werke Edited by:
von Dyck , Walther ,
Caspar , Max ,
Hammer , F. and
List , Martha . Vol. 14, 278–278. Munich (This edition is cited hereafter as ‘KGW’.) The earlier letters to which Kepler refers are now lost. David Fabricius had hoped to meet Kepler during a brief visit to Prague in 1601, but Kepler was in Graz at the time. From Prague, Fabricius wrote the letter of 23 June 1601, which opened the correspondence between the two (see Max Caspar's note inKGW, vol. 14, 481). It would seem that Kepler's first reply to Fabricius was written on 18 July 1602, so that his first mention of the oval orbit to Fabricius cannot have been earlier than this date (see Caspar's note inKGW, vol. 14, 488). Compare the letter of Fabricius to Kepler of 24 September 1602 (KGW, vol. 14, 281).