 Yet one can also see why Bellarmine and the instrumentalists would not have been impressed. First, they did not accept Galileo’s restriction of possible causes to mechanically intelligible causes. Second, Galileo’s explanation is not precise; it does not account for many details of tidal motion. Most significantly, the motion of the Earth’s surface varies over twelve hours, not the six-hour cycle of the tides. Third, the argument does not touch upon the central position of the sun or arrangement of the planets as calculated by Copernicus. So at best, Galileo’s argument is an inference to the best partial explanation from a limited set of features of Copernicus’s theory. Meanwhile, there were compelling considerations about the size of celestial bodies that weighed against the Copernican cosmology, stemming from a lack of understanding of the telescope’s optics (Graney 2015).