Scandalous Error: Calendar Reform And Calendrical Astronomy In Medieval Europe

378 Pages·2018·210.93 MB·English

by  C. Philipp E. Nothaft

OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
SCANDALOUS ERROR
OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
Scandalous Error
Calendar Reform and Calendrical
Astronomy in Medieval Europe
C. PHILIPP E. NOTHAFT
1
OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
3
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In memory of Fritz Saaby Pedersen
(1945–2016)
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OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
Acknowledgements
A sizeable number of institutions and individuals have supported my work on this
book over a period of close to four years. For intellectual support, my greatest debt
of gratitude is owed to Charles Burnett, Leofranc Holford-Strevens, David Juste,
and Immo Warntjes, all four of whom have had a shaping influence on the genesis
of this book. I thank them for their advice and occasional criticism, and for reading
through earlier drafts. On the institutional side of things, I remain immensely
grateful to the administration and staff of the Warburg Institute and to the Warden
and Fellows of All Souls College, who confirmed their respective reputations as
patrons of abstruse scholarship by offering me a place to work (and live). I also
thank the numerous libraries and research institutions—too many to mention—
who have granted me access to their holdings or furnished me with reproductions
of their manuscripts. Above all, my thanks are due to the library staff of the
Monumenta Germaniae Historica (Munich), in particular to Arno Mentzel-
Reuters and Tonja Müller-Tamke, for providing swift and repeated access to their
microfilm holdings. Many further individuals deserve at least a brief mention for
their positive influence on this project, whether as correspondents, editors, confer-
ence hosts, mentors, or conversation partners. I thank, in alphabetic order:
Matthew Champion, Michał Choptiany, Karen Desmond, Sten Ebbesen,
Mordechai Feingold, Giles Gasper, Anthony Grafton, Robert Halleux, Matthieu
Husson, Rob Iliffe, Alfred Lohr, Magnus Löfflmann, Edouard Mehl, Dáibhí Ó
Cróinín, James Palmer, Fritz Pedersen (†), Olivier de Solan, Sacha Stern, Noel
Swerdlow, Faith Wallis, and Helmut Zedelmaier.
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OUP CORRECTED PROOF – FINAL, 24/01/18, SPi
Contents
List of Illustrations xi
List of Tables xiii
Preface xv
Abbreviations xix
Introduction 1
1. The Julian Calendar and the Problem of the Equinoxes in
the Early Middle Ages 14
1.1. Macrobius on the history of the Roman calendar 14
1.2. Calendrical ideal and astronomical reality 18
1.3. Caesar’s reform in Irish monasteries 22
1.4. Medieval calendars and conflicting equinoxes 26
1.5. New impulses: Astrolabes and ‘modern’ dates 34
2. The Ecclesiastical Lunar Calendar and its Critics, 300–1100 42
2.1. Easter: Cycles and controversies 42
2.2. The emergence of an ecclesiastical lunar calendar 53
2.3. Towards a computus naturalis 64
3. Calendrical Astronomy in the Twelfth Century 80
3.1. Walcher of Malvern and the tipping point of Latin astronomy 80
3.2. Arabs, Hebrews, and Latins in calendrical confrontation 85
3.3. The vagaries of the solar year 95
3.4. Roger of Hereford’s synthesis 106
4. The Consolidation of a Calendar-Reform Debate in
the Thirteenth Century 116
4.1. ‘Vulgar computus’ and the error of the Julian calendar 116
4.2. ‘Philosophical computus’ and the science of the Arabs 125
4.3. Franciscans, the pope, and the Hebrew calendar 143
5. Astronomers and the Calendar, 1290–1500 164
5.1. ‘Enhanced’ calendars in late medieval Europe 164
5.2. Latin astronomy in transition (c.1292–1317) 183
5.3. The Alfonsine turn 189
5.4. Alfonsine worries 197
6. The Papal Reform Project of 1344/5 and Its Protagonists 205
6.1. Jean des Murs and Clement VI’s initiative 205
6.2. A radical proposal 212