stars were remote, fixed in their positions and unchanging, while movement and variance were associated with the planets, closer to the earth. An unusual event in the sky might take place close to the earth, and could therefore be explained within the standard cosmological model. However, if it took place beyond the planets, this indicated that the stars, contrary to what was commonly believed, could not be fixed in a 'firmament'. Astronomers (still working with the unaided naked eye at this time) took measurements of parallax to determine whether an object was near the earth or far away from it. Cesi believed that the Accademia needed to publish something of scientific significance in order to establish its scholarly credibility, and that a book from van Heeck which reaffirmed orthodox Catholic positions would both remove suspicions about the group's activities and pave the way for his return to Rome. Van Heeck's theses however posed a number of problems. He critiqued twelve positions put forward by other astronomers on the origins and location of supernovae. Claiming to use the measurement techniques developed by Tycho Brahe, he concluded that the supernova of 1604 showed no sign of parallax, which meant that the event could not have taken place near the earth, among the planets, but must have been located much further away, among the 'fixed' stars of the firmament or perhaps even further beyond. In this, he agreed with Tycho Brahe and other recent astronomers. However he reconciled this conclusion with the Aristotelian model by arguing that the apparently new star was not new at all; while permanent, like other stars, it was only occasionally visible for special reasons. He went further, accusing those who argued for a fluid heaven of writing contrary to Holy Writ, and attacking Tycho Brahe for his religious beliefs as well as for his purported scientific errors. Broadening his polemic against all erroneous ideas, he attacked Protestantism, thereby drawing Kepler into his argument. The language and tone of van Heeck's text was most intemperate. He berated the 'babbling new Philosophers' for their 'profane ignorance' and 'stupid ostentation' in departing from Aristotle. Cesi greatly esteemed Kepler, and therefore edited van Heeck's text, removing anything hostile to him or to other astronomers. He also removed much of the defence of the Aristotelian cosmology, as it was important for the Accademia to align itself to new astronomical discoveries and not become