Of course, it helped that the same Ilkhānids soon converted to Islam, and granted Ṭūsī what he asked for. And there, in the city of Marāgha Ṭūsī managed to assemble the most distinguished company of astronomers ever assembled in one place. The mere gathering together of such astronomers, at such an active center, equipped with a new library of manuscripts that were rescued from Baghdad and other Iraqi and Syrian towns, together with Ibn al-Fuwaṭī as a librarian, they collectively and individually managed to produce the most sophisticated astronomical theories of Islamic times. Some of them had already made their contribution before they came to Marāgha. Just as Ṭūsī himself had done when he proposed his new mathematical theorem, the Ṭūsī Couple, while he was still at Alamūt, as we have already seen. And as 'Urḍī too did when he had completed his most celebrated astronomical work, and his Lemma, when he was still in Damascus. But their getting together at Marāgha produced the kind of astronomy that Shīrāzī was able to popularize by starting a tradition of dialogue with earlier astronomers, via the cumulative work of commentaries, and when he wrote two very long ones of his own within twenty years from the building of the Marāgha observatory.
More importantly, one should also remember that the foundation of the Marāgha observatory was commenced in the year 1259, that is, exactly one year after the destruction of Baghdad. The engineer who constructed the instruments, and in all likelihood who also built the structures himself, as most of them were masonry structures that doubled as astronomical observational instruments, was none other the famous astronomer/engineer 'Urḍī himself. We are particularly fortunate to have a treatise written by this distinguished engineer, in which he detailed all the constructions that he accomplished at Marāgha, a treatise unequaled in its sophistication and utility, and the likes of which was unknown from the pre-Ghazālī period. Its importance can only be fully appreciated when we learn that it was also used as a guide for the construction of later observatories that were built in Samarqand during the time of Ulugh Beg (c. 1420) and in Jaypur, India, toward the end of the eighteenth century. The text of this treatise remains, unfortunately, unedited in a modern scientific edition, and is only partially translated.[386]
Both of the decline narratives, therefore, that attribute the death of science either to the success of Ghazālī's religious thought, or to the destruction of Baghdad by the Mongols, do not seem to explain the brilliant scientific production we just mentioned. Furthermore, and in light of what we already know, these two causes do not seem to have even slowed down the production of science and did not seem to have set an age of decline. On the contrary, one may argue that the period that followed was marked by an increase in scientific production, and a remarkable upgrading of its quality, so much so, to make the production in the pre-Ghazālī period look much more modest in comparison. And as I have already said, in the field of astronomy alone, I have already argued that the golden age of that discipline, in terms of the production of planetary theories at least, should in fact be located in the post-Ghazālī period.
But if that were the case, and if the age of decline could be so easily reconstructed as an age of fecundity, at least as far as astronomical production was concerned, then when was this age of decline, and what is one to understand by the term decline in the first place? 'Decline' is a relative term implying a comparison between two levels, one perceived to be lower than the other. And as we have just seen, when we compared the scientific writings produced in the post-Ghazālī period, in several scientific disciplines, and found them to be more sophisticated than the ones that were written before, and at times even written in direct opposition to those earlier writings, we were at all times comparing one scientific production against another, and many factors were taken into consideration in this process. On the basis of those comparisons one would have dared to say that the post Ghazālī period witnessed a renaissance in comparison to the pre-Ghazālī period, and thus the latter could in turn be described as an age of decline.
Some of those factors that went into the comparison had to do with the quantity of production, for it is quite natural to expect that a few texts here and there would not make a trend, and thus would not constitute a shift in the type and quality of scientific production. It is for that reason that special attention was paid to the number of scientists in the post-Ghazālī period whose works were considered in the comparison process. And here again, the case of astronomy did not only prove that there were far more scientists from the later period who produced more creative material, but that there were more of them producing material in opposition to the earlier astronomers. One can detect a clear trend of new ways of doing astronomy, and thus one will have to admit that the post-Ghazālī period deserves a special consideration.
Then the number of fields in which this production was compared had to be considered, for it would also be natural not to think of excellence in one field as a sign of a trend that should characterize a historical period as more or less advanced. And there again, the circle was widened to include such disciplines as medicine, optics, and mechanical engineering. In all instances one could find results that were more or less in agreement with what seemed to be happening in astronomy.
And if one were to take a look at the field of scientific instruments, one could also document a similar flourishing activity in this later period, not only in the remains of large scale observatories such as the ones that were built in Marāgha and Samarqand, but also include those that were built by Jai Singh II (1686-1734) in India in imitation of those earlier ones.[387] One can also notice, from the sheer number of scientific instruments, still kept at Museums all over the world, whether astrolabes, quadrants, sextants, or what have you, that the number of more and more refined instruments kept increasing in the later period. To take only one example, the development of the universal astrolabe, of which we still have several samples, is not only a masterpiece of workmanship, but is also theoretically superior to the astrolabes that were constructed in the earlier period. And so was the case with many other instruments.[388] Thanks to the abundant results that are now in print, one can simply assert that the field of astronomical instruments also witnessed a "golden age" in the post-Ghazālī period, in complete synchrony with the field of planetary theories, although the two fields are only poor cousins.
I know the number of disciplines that I have attempted to list here is by no means exhaustive, and here I must admit that lack of competence in the history of other disciplines restrains me from passing judgments about them in the same fashion. But I certainly welcome colleagues who work in those disciplines to double check the results that have been so obviously achieved so far and decide for themselves whether this period can still be called a period of decline. My suspicion is that we have surveyed a good representative cross section of disciplines. And most probably the results we have already achieved, and the assessments we are now making, will withstand such additional tests from other disciplines.
While it is true that most of those results point to an increased volume of brilliant astronomical production, all coming from the post-Ghazālī period, nevertheless none of those results seem to come from the relatively later period, namely, the period beyond the sixteenth century, as far as I know. Again for the field of astronomy, I dare say that this may be due to lack of expertise on my part, since I have not thoroughly investigated the later works. I have focused over the last two decades or so on the works that were produced between the thirteenth and sixteenth centuries, and have not paid enough attention to the mostly inaccessible works of the later centuries. Disciplines other than astronomy may have suffered from similar handicaps, and thus may one day turn out new material that is still undiscovered.
387
On the Marāgha, Samarqand, and Jai Singh II observatories, see Sayīlī,
388
For the field of scientific instruments in general, see the works of David King,