The Copernican model replaced Ptolemy's equant circles with more epicycles. 1500 years of Ptolemy's model, help create a more accurate estimate of the planets motions for Copernicus. This is the main reason that Copernicus' system had even more epicycles than Ptolemy's. The more epicycles proved to have more accurate measurements of how the planets were truly positioned, "although not enough to get excited about". Over the years, the Ptolemaic system become less reliable and less accurate which became obsolete to Copernicus's system. The Copernican system can be summarized in several propositions, as Copernicus himself did in his early "Commentariolus" that he handed only to friends, probably in the 1510s. The "little commentary" was never printed. Its existence was only known indirectly until a copy was discovered in Stockholm around 1880, and another in Vienna a few years later.