The Speculum Astronomiae and Its Enigma W. Vogel & M. Büttner GmbH Interesting ma terial from the O.P Interesting ma terial from the interior started to reach the Dutch museums in ever increasing numbers after the late nineteen thirties when Dr Several methods for the assessment and measurement of quality of life have been borrowed from the UK and the US and then further developed in northern Europe Mandonnet's theses were refuted by Lynn Thorndike and have since then been the subject of widespread discussion The Speculum drew the fundamental outlines of this discipline into a theoretical and bibliographical introduction no small achievement and was consequently greeted with great interest and used as a standard reference book for many centuries