Produced by Thorsten Kontowski, Paul Clark and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.) [ Transcriber's Note: Every effort has been made to replicate this text as faithfully as possible, including inconsistencies in spelling and hyphenation. Some corrections of spelling and punctuation have been made. They are listed at the end of the text. Italic text has been marked with _underscores_. Bold text has been marked with =equals signs=. Text marked ^{thus} was superscripted. ] [Illustration] THE SUN changes its position in space, therefore it cannot be regarded as being "in a condition of rest." _Si concedimus, eos, qui corpora in mundi spatio moveri eademque non moveri posse dicunt, insulsa loqui, praesumere non licet hominem astronomum talem sententiam elocuturum utque eam demonstraret operam daturum esse._ By August Tischner. Leipzig, Gustav Fock. 1883. Dedicated to all friends of Rational Astronomy. [Illustration: _Nicolaus Copernicus._ _Terrae motor, solis stator._] The system of Copernicus is the only possible system; it is the eternal base of all astronomical progress, with this system the science of Astronomy stands and falls, and without it we must give up all explication as well as every scientifically founded predication. Hence it is clear that an astronomer of the present day cannot enter upon any other system, even by way of trial. Dr. _J. H. Mädler_. Popul. Astr. 1861. p.p. 48. 54. 62. _An army of philosophers will not suffice to change the nature of an error and to convert it into truth. Ebn-Roshd (Averrhoës), Arabian philosopher of the XII^{th} century._