section_path: Copernican system/Copernicus
section_name: Copernicus
paragraph_text: Copernicus
  
  Copernicus's major work on his heliocentric theory was Dē revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), published in the year of his death, 1543. He had formulated his theory by 1510. "He wrote out a short overview of his new heavenly arrangement, also probably in 1510, and sent it off to at least one correspondent beyond Varmia. That person in turn copied the document for further circulation, and presumably the new recipients did, too..."
  
  Copernicus's Commentariolus summarized his heliocentric theory. It listed the "assumptions" upon which the theory was based, as follows:
  
  De revolutionibus itself was divided into six sections or parts, called "books":