- I dintorni dell'infinito: Giordano Bruno e l'astronomia del Cinquecento
Whoever might have wondered what Giordano Bruno actually knew, or could or should have known, about astronomy, here is the book that explains nearly [End Page 926] everything in great detail. Among the many studies on Giordano Bruno's philosophy, only few go into the technicalities of Renaissance astronomy compared with Giordano Bruno's scientific claims. Several articles by Miguel A. Granada are the exception. Granada indeed receives credit for having helped craft the book that originated as a PhD dissertation with Pietro Redondi as supervisor.
In four large chapters the author addresses the position of earth and moon, the system of the planets, the nova of 1572, and the comets. The first chapter compares the Copernican interpretation of the spherical system with the true or alleged Pythagorean cosmology. For the problem that had vexed many interpreters of Giordano Bruno is that in his Cena de le ceneri he maintains to possess the correct interpretation of the Copernican system through reading his diagram of the planets as though the earth and the moon formed an epicycle on a virtual orbit around the sun. (Tessicini does not take into account the options that the Latin wording of Copernicus was ambiguous or that Bruno was handling a manuscript when he argued the dot on the orbit of the diagram that could mean the earth was but a puncture caused by the compass.) The author appraises the tradition of Pythagorean astronomy and its reception in the sixteenth century, which explains another riddle in Bruno's works, namely, the assertion that Mercury and Venus form a similar epicycle. It turns out that this was a variation of the Pythagorean notion of an antiterra: an invisible planet that would complete the number of spheres. While opposing Copernicus here, Bruno followed his lead in the rearrangement of the planetary system starting from the position of earth and moon. The benefit for the interpretation of Copernicus is that his reference to Pythagoras in his De revolutionibus was then not merely rhetorical, but meant as a reference to a scientific pattern that allowed to position the sun in the place of the "central fire." This does not exclude rhetorical deployment, at least not in Copernicans like Thomas Digges. But it is obvious that Giordano Bruno "superimposed the cosmology [of the Pythagorean Philolaos] as explained by Aristotle over that of Copernicus" (51).
This discussion is followed up concerning the entire system of planets in chapter 2. One of the most important insights provided by this study is that even in pursuing Pythagorean alternatives early modern thinkers remained at the mercy of Aristotle, who provided them with their conceptual and historical means. The complicated debate about the new planet of 1572 gives an opportunity to discuss the nature of mathematics and hypotheses in sixteenth-century astronomy. In insisting that according to the Aristotelian system new stars, and even comets, are beyond nature, and thus miraculous, Bruno does not advocate Galilean mathematics but extends the laws of universal nature beyond the sphere of the moon, a cosmological method that would nevertheless come in handy for the mathematization of nature. Bruno's talking about planets as earths (terre) conceptually paved the way for the discovery of new stars. Johannes Kepler almost always concludes the treatment of an astronomical problem in this book, which creates the expectation that Kepler might be the right key to interpret Bruno, an intriguing suggestion for a further study, which might also address the question when and [End Page 927] where one has to distinguish scientific-astronomical from cosmological-philosophical thoughts.
Although the book has an index of names, the reader misses an index of concepts and a bibliography. The book is hardly accessible even to those who read Italian with ease because of its long and convoluted sentences (beyond what goes for elegant and less witty than the title of the book promises) and the equally...