The ArgumentThe publication of Johannes Kepler's brilliant and revolutionary Astronomia nova has hitherto been viewed as somehow inevitable. This paper argues that, on the contrary, the book's very existence and a measure of its unusual form and content are in fact highly contingent, and derive from a legal dispute between Kepler and Tycho's heirs over the right to capitalize on his astronomical legacy. On Tycho's death, Kepler rather accidentally found himself in charge of Tycho's posthumous astronomical publications, especially the highly (...) prestigious Rudol phine Tables. Tycho's legal heirs, not having been paid by the emperor for Tycho's astronomical assets and feigning Kepler's unworthiness as his successor, wrested this mandate back. Ordered in turn to justify his employment, Kepler contrived the Astronomia nova as an interim announcement of the fruits of his astronomical research. In an effort to block Kepler's continuing exploitation of Tycho's observations, the heirs obtained the legal right to censor his publications, which severely threatened his philosophical freedom. The threat of editorial interference was responsible in part for Astronomia nova's unusual narrative form. (shrink)