History of physics to simplify their production. In heliocentric models of the Solar system, the Earth orbits the Sun along with other bodies in Earth's galaxy, a contradiction according to the Greek-Egyptian astronomer Ptolemy (2nd century CE; see above), whose system placed the Earth at the center of the Universe and had been accepted for over 1,400 years. The Greek astronomer Aristarchus of Samos (c.310 – c.230 BCE) had suggested that the Earth revolves around the Sun, but Copernicus' reasoning led to lasting general acceptance of this "revolutionary" idea. Copernicus' book presenting the theory ("De revolutionibus orbium coelestium", "On the Revolutions of the
Theory of the Earth evidence of the past action of processes which still operate today. He also anticipated natural selection, as follows: Hutton's prose hindered his theories. John Playfair in 1802 restated of Huttton's geological ideas in clearer English. However, he left out Hutton's thoughts on evolution. Charles Lyell in the 1830s popularised the idea of an infinitely repeating cycle (of the erosion of rocks and the building up of sediment). Lyell believed in gradual change, and thought even Hutton gave too much credit to catastrophic changes. Hutton's work was published in different forms and stages: Theory of the Earth Theory of the Earth