The previous year, Tycho, in a letter, had expressed the hope that Kepler would ‘some day’ visit him. Though Kepler was panting and pining for ‘Tycho’s treasure’, the invitation was couched in too general terms, and the journey too long and costly. Now, however, it was no longer a matter of scientific curiosity for Kepler, but of the urgent necessity of finding a new home and a livelihood.
