The Dialogue Concerning the Two Chief World Systems was an attempt by Galileo to promote the heliocentric theory of the universe. In the Copernican system the Earth and other planets revolved around the sun, while in the Ptolemaic system everything in the universe circles around the Earth. The Dialogue, published in Florence under a formal license from the Inquisition, attempted to skirt the controversy by couching the discussion in a fictional dialogue between Aristotle, Copernicus, and Ptolemy. The ruse was unsuccessful, and in 1633 Galileo was convicted of grave suspicion of heresy. Galileo was imprisoned, and in the Dialogo was placed on the Index of Forbidden Books, from which it was not removed until 1835.