Galileo, Dialogo

Galileo Galilei (1564–1642).
Dialogo . . . sopra i due massimi sistemi del mondo Tolemaico, e Copernicano.
Florence: Giovanni Batista Landini, 1632. (BRA0851)

Class II: Prohibited Titles

Galileo’s “Dialogue Concerning the Two Chief World Systems, Ptolemaic and Copernican” remains one of the most significant books in the history of science. Controversy arose over Galileo’s proof of the Copernican cosmology, which placed the sun, not the Earth, at the center of the solar system. This contradicted the biblical statement in Joshua 10:13 that God had made the sun stand still in the sky over the earth. Prohibited in 1634, Galileo’s Dialogo remained on the Index until 1824.

The engraved frontispiece depicts three great students of astronomy in dialogue: from left to right, Aristotle (384–322 BCE), Ptolemy (90–168 CE), and Nicholas Copernicus (1473–1543). Ptolemy holds an armillary sphere with the Earth at its center, while Copernicus grasps a heliocentric model of the solar system.