Perugia: Marci Naccarini, 1619. 4to. 72 pp. FIRST EDITION. Engraved title vignette of one of the 1618 comets in the constellation of Libra, with large historiated initials and text diagrams. Antique calf in a contemporary style with gilt borders and gilt- ornamented spine; overall in superb condition. Item #13784
First edition of Grassi’s extraordinarily important and bitter attack on Galileo’s theory of the nature of comets, later inspiring Il Saggiatore. The scientists’ famous dispute started the prior year with Grassi’s De tribus cometis, which Galileo (using the alias of his assistant Guiducci) followed up with his provocative Discorso della comete (1619). Grassi responded (under the pseudonym Lothario Sarsi) with this publication of Libra astronomica, in which he strongly defends the ideas of Tycho Brahe and the Jesuits. Galileo went on to publish his polemic and rhetorical masterpiece, Il Saggiatore, as a direct reply to this work.
Grassi (1583-1654) was a Jesuit mathematician who taught at the Collegio Romano. This controversy ruined his relationship with Galileo, and earned his adversary the ire of the entire Collegio Romano — a major factor in his later difficulties with the Inquisition.