Copernicus. De revolutionibus orbium coelestium.

Nicolaus Copernicus. De  revolutionibus orbium coelestium. Basileae: Ex officina Henricpetrina, 1566.

Copernicus’s revolutionary work on planetary motion was first published in Nuremberg in 1543. The text was completed as early as 1530, but Copernicus was reluctant to publish. He was eventually persuaded to commit to print by Georg Joachim Rheticus of Wittenberg. Copernicus, however, never saw his finished work, as he died on the eve of its publication. The work did not have an immediate impact, and a second edition was not required until 1566. De revolutionibus refuted the Ptolemaic system of a fixed earth, around which the sun, moon and planets revolved. By placing the sun at the centre of the system, with the earth spinning on its own axis, and circling the sun in common with the other planets, the whole system of the heavens became simple, clear and harmonious. Copernicus believed, however, that planets moved in epicycles. It was Kepler who eventually demonstrated that planetary movement around the sun was elliptical. The book evaded the scrutiny of the Church until 1616 when it was brought to the attention of the Inquisition through Galileo's writings, and was placed on the Index librorum prohibitorum.