De libris revolutionum Copernici narratio prima, usually referred to as Narratio Prima (Latin: First Account), is an abstract of Nicolaus Copernicus' heliocentric theory, written by Georg Joachim Rheticus in 1540. It is an introduction to Copernicus's major work, De revolutionibus orbium coelestium, published in 1543, largely due to Rheticus's instigation. Narratio Prima is the first printed publication of Copernicus's theory. Source: Wikipedia (en)