At the front of the green octagonal table in the Linder Gallery, very prominently positioned in the painting, is a scrap of paper bearing three competing systems of the universe: the Ptolemaic earth-centred system at the top left, the sun-centred Copernican system (prohibited by the Inquisition since 1616) and the compromise system of the Danish astronomer, Kepler’s mentor Tycho Brahe, …