All those shifts in astronomical thought that took place in Islamic civilization had some very serious consequences. Not only did they expose all the factual and observational errors of Greek astronomy, but also demonstrated, in the most convincing manner, the inconsistencies of that astronomy with its very own cosmological presuppositions. In the later centuries, when Islamic astronomy reached its theoretical maturity, starting with the continuous rise of analytical discussions of planetary theories after the thirteenth century, one could hardly find a serious astronomer who did not make an attempt at reformulating Greek astronomy. At that time, no one could hope to practice astronomy, and be taken seriously, if he did not make an effort to solve the thorny cosmological problems of Greek astronomy. One astronomer after another, tried their hand at devising new mathematical models that represented a much more consistent cosmological picture of the Greek astronomical tradition. At the same time, those models could account perfectly well for the same observations, which were used by Ptolemy, in the first place, to construct his own predictive mathematical models for planetary motions.
This constant search for more consistent representations of planetary motions came to characterize the whole field of Islamic astronomical research, especially in the later centuries following the thirteenth century. The movement of continuously reforming Greek astronomy became so important that it apparently attracted the attention of astronomers from outside the Islamic domain. We know, for example, that Byzantine astronomers, like Gregory Chioniades (fourteenth century) and others, would travel to the Islamic lands in order to learn of the latest developments in Islamic astronomy and to report their findings back to their compatriots in their own Greek language.[305] In fact, one can also document the dependence of the late Byzantine astronomy on Islamic astronomy by simply browsing through the technical terminology that was used by Byzantine astronomers at the time. This terminology demonstrates very clearly that it bore a much closer resemblance to the Arabic sources, from which it was derived, than to the classical Greek texts such as those of Ptolemy.[306]
With the fall of Constantinople in 1453 to the Ottoman Turks, and the ultimate demise of the Byzantine empire, a good number of Byzantine scholars escaped westward, at times together with their books. But by then the Byzantine civilization had been in direct contact with the Islamic civilization for centuries already. And as a result those books inevitably bore the marks of having been influenced by the intellectual production of the Islamic civilization, and thus contained some of the developments that had already taken place in that civilization. In a way, these Byzantine contacts with Europe were much more complex than the contacts that had already taken place during the Middle Ages between the Islamic world and the Latin West. In the first, we saw several Arabic works that were translated into Latin, sometimes undigested, and mostly restricted to the confines of linguistic contours of the texts. With the new Byzantine contacts one can now distinguish a new manner of transfer of texts. Arabic and Persian scientific texts were apparently already digested in the Byzantine Greek sources for a period of about two centuries or so, before those Byzantine texts were brought into Europe. This time, their contents were not apparently translated into Latin. Rather, because of the emphasis of the Renaissance intellectual environment on the Greek language, they were read in the original Greek. The best of their contents, which were originally Arabic and Persian could now be directly assimilated into the Latin texts, without having to translate the whole text into Latin. This method of transfer of knowledge constitutes by itself a new phenomenon that is rarely acknowledged by all those who study the transfer of knowledge across cultures. More importantly, this later transfer of knowledge from the world of Islam to Europe this time spoke directly to the contemporary science of the Renaissance, where its impact can be best detected, as we shall soon see.
About the same period that witnessed the various contacts between Byzantium and the world of Islam there were various other contacts as well. One should pay attention to the several European travelers who performed their pilgrimage to the Islamic world, either to visit the Holy Lands, or to simply seek knowledge from the lands of Islam. This contact too must have brought some of the findings of the Islamic world to the European countries. What did they bring in particular is a matter that is currently under investigation and promises to produce some very interesting results.
Our current state of knowledge, however, can already inform us about some of those contacts and the nature of the information that was exchanged. We already know, for example, that those contacts brought some very advanced theoretical findings from the lands of Islam to Renaissance Europe, findings that were apparently highly appreciated by the
European scientists who consumed this material and ended up incorporating it in their own works.[307] And yet our research in that particular area is still in its infancy and once it is completed, it promises to change much of our world view, about cultural transmissions, cultural contacts, the nature of the European Renaissance, and the earliest roots of modern astronomy.[308]
A sheer accident, in 1957, brought to the attention of Otto Neugebauer, who was then working on the mathematical astronomy of Copernicus, a text that contained the theoretical astronomy of the famous Damascene astronomer Ibn al-Shāṭir (1375). It did not take the genius of Neugebauer much, despite the fact that he did not read Arabic himself, to realize that Ibn al-Shāṭir's lunar model was indeed identical, in every respect, to that of Copernicus (1543) (figure 6.1). The former model, has survived in Ibn al-Shāṭir's text Nihāyat al-sūl fī taṣḥīḥ al-uṣūl (Final Quest Regarding the Corrections of the [Astronomical] Principles), and was brought to Neugebauer's attention by his close associate and friend Edward Kennedy. Kennedy was then a professor of mathematics at the American University of Beirut, and a distinguished historian of Islamic astronomy and mathematics in his own right. His own encounter with Ibn al-Shāṭir's work at the Bodleian Library was in itself a pure accident as well, and now belongs to the world of legends. But that discovery, together with its ensuing discussion with Neugebauer, gave rise to the publication of an article in Isis by Victor Roberts, a student of Kennedy, who called it "The Solar and Lunar Theory of Ibn al-Shāṭir: A pre-Copernican Copernican model."[309]
Naturally, such a finding jolted the scholarly community somewhat, for up till then the prevailing belief was that Renaissance science, unlike its medieval counterpart, was considered to be a European self-contained creation, almost ex nihilo. Or if one were to widen his horizons and look outside the particular confines of the European environment one was supposed to find Renaissance science taking its inspiration from the classical Greek sources, rather than any other source, least of all Islamic sources. Common opinion stipulated a European enmity with things Arabic and Islamic and thus no one would have expected a fruitful contact between the two.[310] For Neugebauer to find that there was a direct connection between the works of Copernicus and the Arabic planetary theories, which were produced in the Islamic world about 200-300 years before, was a discovery that was shocking in its own time and has not been fully digested yet in the secondary sources dealing with the history of science in general. Only a handful of researchers seem to know about it still, and to appreciate its full significance.
305
See David Pingree, "Gregory Chioniades" and
306
See O. Neugebauer, "Studies in Byzantine Astronomical Terminology"; G. Saliba, "Arabic Astronomy in Byzantium",
307
See G. Saliba,
309
Victor Roberts, "The Solar and Lunar Theory of Ibn al-Shāṭir: A pre-Copernican Copernican Model",
310
A glimpse of the status of Arabic in some European quarters, especially among the humanists, can be gained from the advise given by Hernan Nuñez, a professor at the University of Salamanca, a most friendly place for Arabic studies to Copernicus's contemporary, Nicolas Clenardus of Louvain (1495-1542), who had traveled, around 1530-1532, all the way from Louvain to Salamanca, in search of an Arabic professor, only to be told by Nuñez: "What concern have you with this barbarous language, Arabic? It is quite sufficient to know Latin and Greek. In my youth I was as foolish as you, and, not content with adding Hebrew to the other two languages, I also took up Arabic; but I have long given up these last two, and devoted myself entirely to Greek. Let me advise you to do the same." (quoted in Karl Dannenfeldt, "The Renaissance Humanists and the Knowledge of Arabic",