The notion of scientific achievement may have both descriptive and normative meanings, and it may refer to an act of individual discovery as well as to the tradition of research founded upon that innovation. The essays gathered in this volume to honour the 500th anniversary of the birth of Nicholas Copernicus well illustrate the diversity of issues that may be assembled under the rubric and "Copernican Achievement and ". Finely honed technical analyses of Copernicus' astronomy; studies of his early formative years at the university; the intriguing circumstances surrounding the publication of De revolutionibus and the virtually unknown career of Copernicus' and "editor and ", Andreas Osiander; the complex and difficult question of how the new theory was received by academic natural philosophers and astronomers; the equally demanding philosophical problem of establishing universal conditions according to which the Copernican theory might be compared to the Ptolemaic as a scientific theory; the historical and conceptual preconditions for a scientific revolution of the sort inaugurated by Copernicus - such is a wide range of issues considered in this volume.