The Dialogue Concerning the Two Chief World Systems (Dialogo sopra i due massimi sistemi del mondo) was a 1632 Italian language book by Galileo Galilei comparing the Copernican system with the traditional Ptolemaic system. It was translated to Latin as Systema cosmicum in 1635 by Matthias Bernegger. The book, which was dedicated to Galileo's patron, Ferdinando II de' Medici, Grand Duke of Tuscany and delivered to him on February 22, 1632, was a bestseller. Read more