Giordano Bruno has been seen as a precursor of the scientific revolution and as a martyr for modern science. We examine the significance of his arguments from a strictly scientific viewpoint. In his cosmological dialog, The Supper of Ashes,he defends the Copernican theory and discusses optics and geological change, as well as the ship experiment later to be made famous by Galileo and Gassendi. But even when correct in their conclusions, Bruno's “scientific” arguments do not exhibit any understanding of scientific reasoning or purpose. Rather they serve the totally unrelated function of allegorical descriptions of a metaphysical relationship between Man and God as well as Catholic and Protestant. Bruno sees Nature as the signature of God, and he believes that this signature can best be perceived through the hieroglyph of the Copernican theory.