De revolutionibus orbium coelestium
Novara's writings are largely lost, except for a few astrological almanacs written for the university. But Copernicus' "De revolutionibus orbium coelestium" (published in 1543, long after Novara's death) records that on 9 March 1497 Novara witnessed Copernicus' first observation. Both men were described as "free minds and free souls," and Novara believed that his findings would have shaken Ptolemy's "unshakable" geocentric system.