MILKY WAY VICISSITUDES: MACROBIUS TO GALILEO

Amongst the many astronomical phenomena that have inspired speculation regarding their nature, the Milky Way takes a prominent position. In late antiquity, the Galaxy (from Greek gala, or milk) held pride of place in Martianus Capella"s Marriage of Philology and Mercury and in Macrobius" Commentary on the Dream of Scipio, two texts that transmitted classical astronomical knowledge to medieval Latin Europe. But these works also transmitted pagan beliefs that ecclesiastical authorities found disturbing. One such pagan idea held that the Milky Way was the celestial abode of souls, a belief that had been reported by Heraclides of Pontus, Cicero, Manilius, Numenius, Martianus Capella and Macrobius. Several strategies seemed to have evolved in the medieval era in order to minimize the impact of this pagan notion. One strategy was to demonize the Milky Way, as in Michael Scot"s „Daemon Meridianus" that mortals should fear and avoid. Another strategy would be to ignore the Milky Way altogether, as in Sacrobosco"s popular astronomical textbook De Sphaera Mundi. But the most effective strategy against the pagan idea of the Milky Way as celestial abode would be to remove the Galaxy from the heavens. In antiquity, Aristotle had declared that the Milky Way was an atmospheric phenomenon, thereby removing it from the celestial regions. Although Aristotle"s theory of a sublunary Milky Way had been criticized and mostly ignored in antiquity, it would resurface when Aquinas adopted Aristotle as The Philosopher. It took some time for the Church and university scholars to embrace Aristotle, but his dictum that the Milky Way was an atmospheric phenomenon would become the prevailing view for centuries. Published in 1610, Sidereus Nuncius was arguably the most important booklet in the history of science. There Galileo reported his telescopic confirmation of the Milky Way"s celestial status that, until then, had been denied by the medieval Aristotelian tradition.