After the publication of his edition of Marcus Manilius’s Astronomica in 1579 Joseph Juste Scaliger embarked upon one of the most important projects of his career. Four years of painstaking research would culminate in the publication of his best-known work: Opus Novum de Emendatione Temporum [A New Work on the Correction of Dates]. Unlike his earlier writings, which were all critical editions or translations of classic texts, this mighty tome was Scaliger’s answer to the thorny question of comparative chronology.
Alexander the Great defeated the Persian Emperor Darius III in one of the most memorable encounters in military history: the Battle of Gaugamela. Consult any modern textbook on Alexander and you will be told that the Battle of Gaugamela took place on 1 October 331 BCE. How do we know that this is the correct date? Did the classical historians record that the Battle of Gaugamela was fought on 1 October 331 BCE? Of course not. No calendars that were in use back then had any such month as October, and no one reckoned the date of any event in terms of how many years it occurred before the birth of Jesus Christ, which had not yet taken place.
What we actually read in the ancient histories is quite different. This is how Plutarch records the date in his Life of Alexander:
Now, the great battle against Dareius was not fought at Arbela, as most writers state, but at Gaugamela. The word signifies, we are told, ‘camel’s house,’ since one of the ancient kings of the country, after escaping from his enemies on a swift camel, gave the animal a home here, assigning certain villages and revenues for its maintenance. It so happened that in the month Boëdromion the moon suffered an eclipse, about the beginning of the Mysteries at Athens, and on the eleventh night after the eclipse, the armies being now in sight of one another, Dareius kept his forces under arms, and held a review of them by torch-light; but Alexander, while his Macedonians slept, himself passed the night in front of his tent with his seer Aristander, celebrating certain mysterious sacred rites and sacrificing to the god Fear. (Perrin 317)
In another of his Parallel Lives Plutarch writes:
Again, on the sixth day of the month of Boedromion the Greeks defeated the Persians at Marathon, on the third day at Plataea and Mycale together, and on the twenty-sixth day at Arbela. (Perrin 139)
Plutarch flourished at the end of the 1st century of the Common Era, so he would be considered a secondary source. But we do possess a contemporary primary source, a Babylonian Astronomical Diary that was probably compiled around the time of the battle:
The 13th [day of the 5th month Abu] ... [lunar] eclipse in its totality covered ...
That month [6th month Ulūlu], on the 11th [day], panic broke out in the camp of the king [Darius III] ...
On the 24th [day of Ulūlu] in the morning, the king of the world [Alexander the Great] erected his standard ...
They fought with each other and a severe defeat of the troops of the king [Darius] ... The troops of the king [Darius] deserted him and to their cities ... They fled to the land of Gutium ... (Babylonian Astronomical Diary )
Another secondary source, the Anabasis of Alexander by Arrian, is slightly younger than Plutarch’s Life of Alexander and gives a different date for the battle:
So ended this battle, in the archonship at Athens of Aristophanes and in the month Pyanepsion. Thus Aristander’s prophecy came true, that in the selfsame month in which the moon was eclipsed Alexander’s battle and victory should occur. (Robson 273)
In the Attic Calendar, Boedromion and Pyanepsion were successive months of the year, so there is a clear discrepancy between Plutarch and Arrian.
How should one use primary and secondary sources like these to calculate the date of the battle in, say, the Julian Calendar? That is the sort of problem Scaliger set out to solve when he embarked upon his titanic task. In De Emendatione Temporum Scaliger derives the formulae or algorithms one must use in order to convert a date in one calendar into the corresponding date in another calendar.
Origins
As Anthony Grafton has pointed out, Scaliger had been deeply interested in chronology long before he edited Manilius’s Astronomica. Years later, in Leiden, he would remark to his student Jean de Vassan:
J’ay de tout temps affecté cette matière des temps. (Desmaizeaux 583)
Time has been on my mind since time out of mind. (Grafton 23)
In the summer of 1573, when Joseph Juste Scaliger was living and teaching in Geneva, he hatched several philological projects that would never see the light of day. In August of that year he wrote to his colleague Pierre Pithou—Jean de Vassan’s uncle—seeking the loan of manuscripts of Roman grammatical works:
Your brother mentioned to me that he had left with you a Censorinus, and a Probus on Juvenal. He assured me that if I asked you for them, you would not refuse me, indeed, that you would willingly make them available to me. Well, since I have decided to publish Gellius, Macrobius, and Censorinus together, and have much to say on those authors, it would be most helpful to me if you were willing to let me use both the aforementioned manuscripts and your learned conjectures and notes on the aforementioned authors ... (Tamizey de Larroque 20-21)
The following month, he wrote again to Pithou, renewing his request. In this letter he laid out his plans for three projects (Tamizey de Larroque 25-26):
A corrected edition of the Saturnalia of Macrobius, the Noctes Atticae of Aulus Gellius, and the De Die Natali of Censorinus.
A corrected edition of Marcus Manilius’s Astronomica.
An edition of the satirists Juvenal and Persius, with the scholia to Persius attributed [incorrectly] to Lucius Annaeus Cornutus.
Of these three projects only the second would be completed. But it is the first that interests us here:
These three texts differed considerably in content and form. But they summarized the researches of the late Republican and Augustan scholars on the technical terminology, early history, and astronomical basis of the Roman calendar. Censorinus and Macrobius sketched the development of the calendar from its crudest, early form and compared it with what they called the ‛Greek’—i.e. Attic—lunar calendar on which Numa modelled his own. Censorinus, whose little literary birthday present for Q. Caerellius of AD 238 is one of the strangest of all ancient books, did more. He packed his work with a vast amount of information about historical and mythical dates, calendar cycles, and ominous intervals and days. Confronting these texts naturally forced Scaliger to think seriously about the subject they shared and to review relevant passages in other works—like Varro’s De lingua Latina and Ovid’s Fasti—with which he had long been familiar. (Grafton 1993:36)
Renaissance scholars before Scaliger had attempted to reconcile ancient and modern dates—Theodorus Gaza, Marsilio Ficino, George Trebizond, and Pierre Haguelon, for example—but none of them had ever envisaged so comprehensive a task as Scaliger undertook in 1579. With De Emendatione Temporum Scaliger created a whole new branch of history: comparative chronology.
The long and complicated path Scaliger cleared for his successors in the decade leading up to the publication De Emendatione Temporum in 1583 has been meticulously researched and described by Anthony Grafton, the Henry Putnam University Professor of History at Princeton University, New Jersey, in two of his works:
From De die natali to De emendatione temporum: The Origins and Setting of Scaliger’s Chronology (1985)
Joseph Scaliger: A Study in the History of Classical Scholarship, Volume 2 (1993)
Much of the material that found its way into De emendatione Temporum arose out of Scaliger’s researches into Censorinus. He worked on Pithou’s manuscript of the De Die Natali from the summer of 1574 until at least 1579—in spite of Pithou’s repeated requests for its return (Grafton 1985:104). But this work drew on many more sources besides Censorinus’s curious little book: Macrobius’s Saturnalia, Gellius’s Noctes Atticae, Plato’s Laws, the Roman History of Cassius Dio, the Parallel Lives of Plutarch, the Bibliotheca Historica of Diodorus Siculus, Strabo’s Geography, the historical writings of the Venerable Bede, and many more. And all the time Scaliger had at his elbow the works of his predecessors in this field: the earlier treatises which Scaliger plagiarized and pilloried with equal zest (Grafton 1985:114).
It was probably towards the end of this sustained burst of deep and indefatigable research that Scaliger conceived of De Emendatione Temporum. For such an epoch-making work, its origins were actually quite humble:
Scaliger’s informal letters to his friends Claude Dupuy and Florent Chrestien show him working on chronology as early as 1579-80. The De emendatione makes its first appearance in the modest form of a ‛little computus’ which Scaliger’s usual publisher, Mamert Patisson, hesitated to print. By July 1580 Scaliger was sketching out some ‛petites διατριβαι’ [little diatribes] to accompany it. An unpublished letter to Chrestien brings the picture into better focus. Scaliger, depressed and isolated in ‛Arabia Deserta,’ his term for the Limousin, thanks Chrestien for writing liminary verses for what he calls ‛computus Aethiopicus’. Evidently the little ‛computus’ that Scaliger first set out to publish—and that provoked his first extended writing on chronology—was the Ethiopian text that appears with Scaliger’s translation and commentary in book 7 of the De emendatione. Scaliger’s most comprehensive and systematic treatise began, paradoxically, as an edition of and commentary on a single short text. (Grafton 1985:114-115)
The expansion of De Emendatione Temporum from critical edition of yet another classical text to encyclopaedia of ancient calendars was gradual:
Clearly Scaliger already saw himself as creating something staggeringly new and learned ... At the same time, however, it is also clear that as yet Scaliger only intended to produce something on the order of books 1-4 and 7 of the De emendatione: systematic treatment of past calendars. He does not mention epochs or calendar reform. Evidently the clear and symmetrical structure of the finished book, with its cross-references and logical progression, was not the one that Scaliger first set out to build. That too casts doubt on the traditional historiography. (Grafton 1985:115)
A Long Note
Grafton draws particular attention to an episode in 1580 when Scaliger’s research into an Arabic manuscript of the four gospels led him into chronological waters that almost proved too deep for him. The resulting long note—the manuscript, which Grafton reproduces in an appendix, is now in Leiden University—is a striking witness of Scaliger’s process:
Bits of this note reappear in the De emendatione; it may well be one of the διατριβαι that Scaliger mentioned to Dupuy in 1580, part of his original commentary on the computus Aethiopicus.
The note seems most impressive. It shows Scaliger accurately translating from Arabic, dextrously solving a technical problem, and beginning to investigate recurrent patterns in calendrical cycles—the very line of inquiry that would soon lead him to devise the Julian Period, his most enduring contribution to technical chronology. (Grafton 1985:116-117)
Grafton also points out how Scaliger initially made many mistakes in his computations:
Ironically, these criticisms of Scaliger’s note redound to his credit. The errors show inexperience, not incompetence; anyone who works in chronology makes mistakes in computation and learns the basic epochs only gradually. In any event, he did solve the colophon correctly, and within year or two would be solving far harder problems with far less effort. (Grafton 1985:118)
This long note also suggests how Scaliger came to call his book Opus novum de emendatione temporum:
At the same time, the note gives a strong hint about how Scaliger mastered his new field. The wording of the last phrases in the note suggests that he was using a standard textbook, the Opusculum de emendationibus temporum [Little Work on the Correction of Dates] ascribed to one Ioannes Lucidus Samotheus. (Grafton 1985:118)
Giovanni Maria Tolosani was an Italian theologian, mathematician and astronomer. He was a prior of the Dominican Order at the Convent of St Mark in Florence in the first half of the 16th century. In 1545 he penned one of the first denunciations of Copernicus’s heliocentric theory. Some years earlier he had written his Opusculum de emendationibus temporum, a series of five short treatises on the subject of realigning the calendar to the seasons. This work was published in Venice in 1537 under the pseudonym Ioannes Lucidus Samotheus. Tolosani was only one of many scholars calling for a similar reform, but almost fifty years would pass before the Papacy finally acted. The Gregorian Calendar was introduced in October 1582, just months before the publication of Scaliger’s De Emendatione Temporum.
Grafton has also identified another important source Scaliger was using:
And a second fraction of the note reveals another, more unexpected modern source. Scaliger writes:
‛In the time of Bede the year of the Creation was, according to the Greeks, 6276 ...’
The text Scaliger was trying to correct was not in fact a genuine work of Bede’s but a calendrical work from late eighth-century France which Ioh. Noviomagus had included in his edition of Bede’s Opuscula de temporibus. [Footnote 87: The ‛Canones annalium, lunarium ac decennovenalium circulorum’, most accessible in Patrologia latina, XC, cols 877 ff. See C. W. Jones, Bedae Pseudepigrapha, Ithaca N.Y. 1939, pp. 82-83.] (Grafton 1985:118)
Grafton concludes his discussion of Scaliger’s long note with the following:
The note reveals that he learned standard techniques by working, slowly and painfully, through standard books. When Scaliger needed to deal with a computus, he read similar works by Bede—and perhaps set out at first to produce something rather like the corpus of computuses and technical commentaries that Noviomagus had assembled half century before. (Grafton 1985:119)
Originality
With De Emendatione Temporum Scaliger was breaking new ground—neu gebrochenen Bahn für die
Wissenschaft [a newly broken path for science] in the words of his biographer Jacob Bernays (Bernays 49). But Grafton emphasizes the debt he owed to several other scholars who had blazed the trail before him:
Once we acknowledge that big works of scholarship necessarily embrace much tralatician matter, Scaliger’s achievement seems far less mysterious than he claimed to Chrestien. Western calendar reformers had produced a host of full analyses of the Julian ecclesiastical calendar. Astronomers had attacked the Egyptian, Persian, Syrian and Islamic calendars used in the classic works of Greek and Arabic astronomers, long available in Latin. Hebrew scholars, like the Jews they studied, had long felt the need to understand the relation between the lunar and solar years and the religious laws that sometimes interfered with the normal functioning of the Jewish luni-solar calendar. A number of writers—above all the French doctor Jean Lalamant and the Basle mathematician Erasmus Oswald Schreckenfuchs produced synthetic works which explicated the oriental calendars and tried to do the same for those of the Greeks and Romans, even though the classical sources for these were scanty and superficial. This body of literature gave Scaliger both a model for the structure that he first set out to build and a good many of the building blocks that went into it.
Even the finished De emendatione owes a considerable debt to these books. (Grafton 1985:119)
Another field in which Scaliger is often regarded as a pioneer is astronomical chronology: the use of astronomy to date historical events:
What then of the scholarly tradition that makes Scaliger the first chronologer to have dated historical events by astronomical methods? His command of astronomical texts and techniques certainly informs the De emendatione as a whole, and does much to make Books 5 and 6 impressive. Pocked with long series of numbers, bristling with tables, these formidable books include computed Julian dates for many eclipses and conjunctions, converted Julian dates for dozens of events, and many efforts to connect dateable astronomical phenomena with human history. As early as the first edition, the De emendatione ties the beginning of Alexander’s world empire to the lunar eclipse that preceded the defeat of Darius at Gaugamela—and thus substitutes for the vague traditional date, Olympiad 112, the startlingly precise one ‛after 20 September 331 BC’—a date which remains the cornerstone of later Greek history. Even Scaliger’s sharpest critics admitted his originality in this respect. (Grafton 1985:120-121)
But even here Grafton points out Scaliger’s debt to his predecessors: Pierre d’Ailly, Werner Rolevinck, Johannes Lucilius Santritter, Petrus Apianus, and Paulus Crusius, among others. The latter, in particular, had a decisive impact on the final construction of De emendatione Temporum:
In 1578 Paulus Crusius’s posthumously published De epochis made correct dates for Gaugamela and much else accessible between two covers.
In this short, forgotten book by a long-forgotten Jena professor of history and mathematics, Scaliger encountered the sixteenth-century tradition of serious historical chronology at its best. The result was a revolution in his thinking. As late as fall 1581, as the letter to Chrestien shows, Scaliger meant to write a book about calendars. But in the spring and summer of 1581 he had repeatedly asked Dupuy to find him a copy of a book by a German ‛en forme de correction de Cronique. C’est comme un instruction corrigendi epochas temporum_’ [‛intended to correct chronicles. It’s like an instruction book for correcting dates’]. By 4 September he had received and read Crusius’s book, ‛lequel est fort bon’ [‛which is very good’]. When he then turned, as he apparently did for the last months of 1581 and the first half of 1582, to reconstructing the chief epochs of world history, he did so with Crusius as his guide. Scaliger’s precise dates for the epoch of the Olympiads, the Peloponnesian war, and the era of Diocletian—as well as the Gaugamela eclipse—are merely verifications of or slight refinements on Crusius’s results. (Grafton 1985:123-124)
But Scaliger was never willing to take his sources on faith. To assess their true value he always cast a critical eye over them—the same critical eye that he had been training for almost twenty years:
For throughout [Books 5 and 6 of De Emendatione] Scaliger does more than apply astronomical evidence. He also consistently confronts the Biblical history of Israel and other nations and the patristic histories of early Christianity with the evidence of non-Biblical texts. His aim, made clear by bold direct statement as well as by example, was to show that the Bible was neither complete nor self-contained as a history of man. The chronologer could not date the events it mentioned—far less work out the histories of the non-Jewish nations it described—without constantly referring to non-biblical sources. And the chronologer dared not accept as authorities the accounts of Josephus and Eusebius, which contained both gross errors and deliberate misrepresentations. This aggressively independent and critical approach to the sources has won Scaliger as much praise as his more technical achievements. (Grafton 1985:125)
Calendar Reform
Scaliger’s De Emendatione Temporum was published just one year after the introduction of the Gregorian Calendar, but this was not a central concern of his in undertaking this mammoth work. If anything, the evidence suggests that Book 8, which deals with calendar reform, was added as an afterthought:
So far we have not considered the motive that led Scaliger to pick chronology for special study. The evidence available so far does not enable us to do so. But it does enable us to refute one common theory inspired by Scaliger himself, who writes in the beginning of Book 8 that the reform of the calendar could well seem to be the chief motive for his work.
In fact, Scaliger’s early references to De emendatione do not suggest that he intended to deal with calendrical problems of a practical kind systematically. Moreover, his letters show that the manuscript he sent off to Patisson in June 1582 included ‛seven big books de emendatione temporum’. And the internal dates in Book 8 all come from the very end of 1582 and the beginning of 1583—and thus prove beyond doubt that Book 8 was written last. (Grafton 1985:129)
There is little in Book 8 that could be called original. Scaliger’s opinions on the reform of the calendar—he was opposed to Gregory’s reforms—were largely influenced by earlier treatments:
Claudius Ptolemy’s account of the Calendar of Dionysios (3rd century BCE) in the Almagest.
The treatise on calendar reform by the music theorist Gioseffo Zarlino, which Scaliger is known to have read in the summer of 1582. De vera anni forma, sive de recta eius emendatione was published in Venice in 1580.
But Scaliger did not slavishly follow these pioneers:
In his case, understanding the ways in which others used the Almagest did not lead to emulation. In Ptolemy, he explained, _the names and times of Babylonian and Assyrian kings seem false or corrupt, so nothing certain can be founded on him; far less can he be used as the source for a chronology—save perhaps a fictional one—even if some do try to use him so. (Grafton 1985:130)
Scaliger’s novelty lies in his successful amalgamation of the various disciplines related to chronology—astronomy as well as philology:
In the case of systematic chronology, it would seem, the novelty in the substance of Scaliger’s work lay in large part in the synthesis he created of existing elements ... In his willingness and ability to fuse astronomy, oriental studies, and classical philology, Scaliger had no predecessor. In fact, by doing so he himself became the model after which the polyhistors of the next century and more tried to shape themselves. By 1620 it was clear across Europe that a serious scholar needed the humanities, Hebrew, and mathematics. The uniting of these in one head and one book was Scaliger’s achievement. (Grafton 1985:130)
Scaliger also broke new ground by treating chronology as a purely objective science, and not as evidence of an intelligent design ordering history along numerological lines—which was the approach taken by almost all his predecessors:
But neither this numerological principle nor any other seems to play a significant rôle in the body of the De emendatione. Angels, tables of great conjunctions, and the future are not among those present. Debate about the meaning and nature of time Scaliger relegates to those whose métier requires them to discuss such matters—the philosophers. And at least once he made his opposition to the search for meanings in the past extremely clear. When he read Bucholzer’s Chronologia—which followed Eusebius in ordering history by 50-year Jubilees, and found a ‛secret analogy’ between these and the years of the world—Scaliger denied both Bucholzer’s reconstruction of the cycle and the consequences he drew from it ...
In condemning Bucholzer’s numerological speculation more harshly than his technical error, Scaliger reveals the true novelty of his attitude. The dates he establishes are dates, not lessons. And this deliberate austerity, this concentration on the technical and the soluble, is the feature of the De emendatione that would have seemed most unusual to a practised reader of earlier chronologies. (Grafton 1985:134)
Public Response
Scaliger’s Opus Novum de Emendatione Temporum was published by Mamert Patisson in Paris in the late summer of 1583. Its eight books in folio comprised over 400 pages:
Immediate reactions varied. Achille de Harlay, the parlementaire to whom it was dedicated, failed to thank Scaliger—who took deep offence. But others saw that, as Corbinelli told Pinelli, Scaliger had produced a ‛libro singolare, dove si ammira più questo monstro d’huomo’ [a singular book, by which this monster of a man may be most admired]—a verdict with which even Scaliger’s critics had to agree. (Grafton 1993:141)
Even in Britain, which Scaliger had visited in the 1560s, De Emendatione Temporum had a lasting impact. In his first book of epigrams the Welsh epigrammatist John Owen, under the title O Tempora! O Mores! [Oh What Times! Oh What Customs!], wrote:
Scaliger annosi correxit tempora mundi :
Quis iam, qui mores corrigat, alter erit?”Learned Scaliger the World’s deformed times reformed :
Who shall now reform men’s crimes? (Owen 1:16 : Thomas Harvey)
The poet John Donne entered a less than flattering epigram on a flyleaf of his copy of De Emendatione Temporum. It is addressed Ad Autorem [To the Author]:
Emendare cupis Joseph qui tempora, Leges
praemia, Supplicium, Religiosa cohors
Quod iam conantur frustra, Conabere frusta;
Si per te non sunt deteriora sat est.You, Joseph, who want to improve the times,
Will hardly succeed where laws, rewards, punishment
And the horde of clergy already failed:
It is enough if you don’t make them worse.
(Donne 12 : Mordechai Feingold 56)
References
- Jacob Bernays, Joseph Justus Scaliger, Wilhelm Hertz, Berlin (1855)
- Pierre Desmaizeaux (editor), Scaligerana, Thuana, Perroniana, Pithoeana, et Columesiana, Volume 2, Prima Scaligerana, Secunda Scaligerana, Covens & Mortier, Amsterdam (1740)
- John Donne, The Epigrams, Epithalamions, Epitaphs, Inscriptions, and Miscellaneous Poems, Edited by William McClung Gary, A Stringer, & Jeffrey Johnson, The Variorum Edition of the Poetry of John Donne, Volume 8, Indiana University Press, Bloomington (1995)
- Mordechai Feingold, Scaliger in England, Ann Blair & Anja-Silvia Goeing (editors), For the Sake of Learning: Essays in Honor of Anthony Grafton, Pages 55-72, Brill, Leiden (2016)
- Anthony Grafton, From De die natali to De emendatione temporum: The Origins and Setting of Scaliger’s Chronology, Journal of the Warburg and Courtauld Institutes, Volume 48, Pages 100–143, The Warburg Institute, The University of Chicago Press, Chicago (1985)
- Anthony Grafton, Joseph Scaliger: A Study in the History of Classical Scholarship, Volume 2, Historical Chronology, Clarendon Press, Oxford (1993)
- Philippe Tamizey de Larroque (editor), Lettres Françaises Inédites de Joseph Scaliger, Alphonse Picard, Paris (1884)
- John Owen, Epigrammata, Johannes Schweighauser, Basel (1766)
- Bernadotte Perrin, Plutarch’s Lives, Volume 2, Themistocles & Camillus : Aristides & Cato Major : Cimon & Lucullus, Loeb Classical Library, L047, Harvard University Press, Cambridge, Massachusetts (1914)
- Bernadotte Perrin, Plutarch’s Lives, Volume 7, Demosthenes & Cicero : Alexander & Caesar, Loeb Classical Library, L099, Harvard University Press, Cambridge, Massachusetts (1967)
- Pierre Pithou (editor), Pervigilium Veneris, Hendrik Scheurleer, The Hague (1712)
- Ernest Iliff Robson, Arrian, Volume 1, Anabasis Alexandri, Books 1-4, Loeb Classical Library, L236, Harvard University Press, Cambridge, Massachusetts (1914)
- Joseph Juste Scaliger, M Terentii Varronis Opera, Third Edition, Robert III Estienne Paris (1581)
- Joseph Juste Scaliger, Epistle against the Barbarous, Inept and Unlearned Poem of Insulanus [François de Lisle], Patronizer of Lucan, Mamert Patisson, Paris (1582)
- Joseph Juste Scaliger, Opus Novum de Emendatione Temporum [A New Work on the Correction of Dates], First Edition, Mamert Patisson, Paris (1583)
Image Credits
- Joseph Juste Scaliger: Nicolas Eustache Maurin (painter), François-Séraphin Delpech (engraver), Bibliothèque de Genève, Public Domain
- The Battle of Gaugamela: Pietro da Cortona (artist), Capitoline Museums, Rome, Public Domain
- Alexander and Darius at Issus or Gaugamela: The Alexander Mosaic, House of the Faun, Pompeii, National Archaeological Museum, Stella (Rione Sanità), Naples, Public Domain
- South Wing of the Collège de Genève: Mourad ben Abdallah (photographer), Public Domain
- Pierre Pithou: Pierre Louis van Schuppen (engraver), Château de Versailles, Versailles, Public Domain
- Anthony Grafton: © The Trustees of Princeton University, Fair Use
- Pierre Pithou’s Edition of the Pervigilium Veneris: The Birth of Venus, Sandro Botticelli (artist), Uffizi Gallery, Florence, Public Domain
- Château de Chantemille: © Aubussonais (photographer), Creative Commons License
- A Page from Scaliger’s Long Note: 12th-century Arabic MS of the Gospels, Endpaper Annotated by Scaliger, Leiden University Library, MS Or. 225 (Appendix II, p. 136), Leiden, Public Domain
- Title Page of Opusculum de emendationibus temporum: Giovanni Maria Tolosani, Opusculum de emendationibus temporum, Lucantonio Giunta, Venice (1537), Biblioteca Europea di Informazione e Cultura, Milan, Public Domain
- Convent of St Mark, Florence: Anonymous Photograph, Copyright Unknown, Fair Use
- The Last Chapter (Venerable Bede): James Doyle Penrose (artist), Cambridge University Library, Public Domain
- Title Page of Johannes Lalamant’s Exterarum...: Johannes Lalamant, Exterarum fere omnium et praecipuarum gentium anni ratio, et cum Romano collatio, Jean Crespin, Geneva (1571), Public Domain
- Erasmus Oswald Schreckenfuchs: Johann Theodor de Bry (engraver), Public Domain
- Title Page of Paulus Crusius’ De Epochis: Paulus Crusius, Liber de epochis seu aeris temporum et imperiorum, Johann Thomas Freigius, Basel (1578), Public Domain
- Jena University (1600): Anonymous Engraving, Public Domain
- Blood Red Lunar Eclipse: Shutterstock, After NASA, Public Domain
- Lunar Eclipse 20 September 331 BCE: NASA Eclipse Website, Eclipse Predictions by Fred Espenak and Jean Meeus (NASA’s GSFC), Fair Use
- Pope Gregory XIII: Anonymous Portrait, Public Domain
- Gregorian Calendar 1582: Aloysius Lilius, Lunario Novo, Secondo la Nuova Riforma della Correttione del l’Anno Riformato da N.S. Gregorio XIII [New Almanac, According to the Newly Reformed Calendar of His Holiness Pope Gregory XIII], Vincenzo Accolti, Rome (1582), Public Domain
- Abraham Buchholzer: Christian Winckler (engraver), After Christian Ezechiel (artist), Stadtbibliothek Breslau (now Wrocław University Library) Public Domain
- Title Page of Chronologia: Abraham Buchholzer, Chronologia, Ambrosius Fritsche, Görlitz (1585)
- Achille de Harlay: Charles Perrault, Des hommes illustres qui ont paru en France pendant ce siècle, Volume 2, Before Page 50, Antoine Dezallier, Paris (1700), Public Domain
