Showing posts with label calendar. Show all posts
Showing posts with label calendar. Show all posts

04 January 2023

Infirmities of Time

As a new Gregorian year sets in, and as we start a new year of Arabic readings, this week’s passage of Ibn Mājid’s Fawā’id could not be more appropriate for a good reflection on the passing of time.

In one of his trademark digressions from the hard technical details of his craft, Ibn Mājid launches into a lengthy poem lamenting the swift passage of time, speaking of lovers in the night, turtledoves, wine and stringed instruments—all the usual imagery of medieval Arabic love poetry—“pierced by dawn and by the muezzin’s voice as if by an arrow.” All this, remember, at the end of a lengthy chapter on sailing seasons, and on the calendrical accuracy and traditional knowledge needed to travel safely across the Indian Ocean. And then comes his reflection after the poem,

“It may be that the monsoon (sailing season) too is afflicted by time with some illness which our minds cannot begin to grasp. Because it is said that every year the season comes later by a quarter of a day of the sphere.”

This ingenious return from the romance of the previous verses to the chapter’s subject matter gives us concrete scientific indications and also a cosmological subtlety.

The scientific indication has to do with the specific solar calendar used by the Arab pilots at the time. It is known that it was a variation of the Yazdgerdi calendar, itself a development of the Zoroastrian calendar, but it is hard to pin down exactly which variant. Here it seems clear that it was a calendar of 365 days without any adjustment for the extra quarter of a day (the tropical year has roughly 365 days and a quarter), and this explains the fact that the seasonal dates were shifting, one day every four years—a known feature of some of the early Persian calendars.

The subtlety has to do with the Arabic word ‘illah, translated here as “illness” and often meaning also a “cause”. Suffice to say that the three semi-vowels central to Arabic writing are called hurūf al-‘ilal, “causal letters” or “letters of infirmity”, corresponding to the Hebrew “mothers of the reading” (imot qeri’ah/matres lectionis)—by being “weak”, like “accidents” of the consonantal fabric, they make articulation possible; they are the efficient causes of articulation.

In this particular case, the infirmity is the ever-uneasy discrepancy between solar days and the solar year (why, oh why can’t the sun return to the equinoctial point in an exact number of days!?). But through this “weakness” in the astronomical fabric, how many changes are set in motion, and how much science has developed!

Ibn Mājid’s point is a sort of poignant physico-lyrical subtlety: the order of the world is full of such little ”cracks”, “weak spots” which are as discreet doors to the forces of causality. They are happy accidents, hotspots for discovery, invention, but also turning points away from every stability, and so unhappy and sad from the point of view of the contented lovers.

As we start a new year, here is to many happy accidents of invention and discovery to our readers and colleagues. Kullu ‘am wa antum bi-khayr! [JA]

30 July 2021

Arab Tridua: Three-Day “Weeks” in Arabia

This post is about a rather neglected aspect of time division in early Arabia. In his Fawā’id (IV, 7) Ibn Mājid explains: “Every month is divided in ten parts of three days each, and each part has its name.” Then he lists the ten triads or, more specifically, tridua: Ghurar, Nufal, Tusa‘, ‘Ushar, Buhr, Bīd, Durā‘, Muhāq, Hanādis, Ziyād, Surar. Most of the names are straightforward in meaning, relating to the appearance of the moon or to the date count, and the word “three” is implicit. For example, “The three of Tusa‘” (al-thalāth al-tusa‘) means something like “the three [days] of the ninth”, because this triad ends on the ninth day of the lunar month. Al-thalāth al-bīd means “the three of whiteness”, because they are near the full moon.

Keen-eyed readers will have noticed that the above list actually contains eleven tridua, not just ten. This means to reflect the garbled textual condition in which Ibn Mājid’s list reached his readers in the 15th century, with obvious ingrained misspellings and interpolations. The earlier references I can find for these names are Ibn Wādih al-Ya‘qūbī (9th century) and al-Bīrūnī (11th century), who give slightly different lists. In comparison to them, Ibn Mājid’s does look like the outcome of centuries of Chinese whispers.

Now, al-Bīrūnī explains first that the names are derived “from the distinctness revealed by the state and the curvature of the moon,” and shortly after that they are “taken from the faces of the moon and its curvature.” This is what I find warrants a thought on our concept of “week”. Our weeks derive in part from a division of the lunar cycle in quarters.

Let us leave aside for now the numerological relevance of the division in three, seven or ten, which we have discussed previously. We can see how the beautiful continuum of the lunation allows for as many divisions as our powers of observation allow us to determine distinct—hence nameable—units. How many nights do we need to appreciate each clearly distinct aspect of the moon?

Nama-rupa, in the Sanskrit philosophical terminology, “name-form”: mutually dependent and inseparable aspects of every phenomenon, everything that appears to then vanish “under the Sun.” The gentle and ever-so-fleeting light of the moon is perhaps the phenomenon par excellence, now there, now vanished… What is left to us, puny sublunary creatures is to wield our power to name, and thus, by naming, to create scientia, the knowability and the knowledge, a “possession for ever.” [JA]

11 January 2021

New Years and Monthless Years

Very aptly, and according to plan, we restarted our reading group last Wednesday with the final session devoted to al-Mahrī’s Qilādah. As far as we are aware, it must be the first time that any shared Western academic initiative has focused on this work in particular, and perhaps even on any work by al-Mahrī. We are grateful to our colleagues in London, Berlin, Leipzig and Abu Dhabi for joining us.

I say very aptly because, as mentioned before, this little treatise is all about the beginning of the year in different calendars, thus about the relations between different calendar eras, and thus about the ever-baffling relations between the paths of sun and moon. To a certain extent it echoes the concerns of computists in medieval Europe for the calculation of the epact.

More specifically, the Qilādat al-shumūs, written by a Muslim pilot, addresses the crucial question of how to reconcile the lunar calendar with the various solar calendars in usage around the Indian Ocean in the late Middle Ages. It was not a theoretical concern, but the very practical one of ascertaining sailing seasons in a region where postponing a departure a few days might have lead to months of delay.

There is one insight from this latest session which has stayed with me after a few days: for most calendrical calculations described, it was necessary to be aware of the number of days elapsed from the first day of the solar year (mā dakhala min al-sanah). This is not unlike the financial “year to date” count, and what in specialised algorithms is nowadays called the dayno. January 11 is simply Day 11, February 1 is Day 32, and March 1 would be Day 60 (i.e. 31+28+1, unless it’s a leap year!) and so on and so forth.

This way of counting the days of the solar year is eminently practical and, remarkably, it does away cleanly with all the layers of mythical and lunar divisions which seem so inseparable from the calendar. It is like stripping the calendar bare and leaving a pure clean sequence of numbers, from 1 to 365. Aniconic, straightforward, arithmetical, almost iconoclastic: what could be more practical?

I wonder if knowing that you were born on the 69th day of the year is of any use at all, or a mere idle curiosity. But when a pilot knew that a certain asterism rose in the morning on the 100th day of the year, he knew unequivocally where this fitted within the cycle of the seasons, and where he was within the rhythm of the monsoons and other seasonal winds.

So let’s get ready and practise: What day of the year were you born, sailor? Don’t give me a date, but what is your birthday’s dayno? [JA]

21 December 2020

Necklace of Suns Excursion

Last week we followed Ibn Mājid’s example and went on an excursion away from our main topic. We did so, nonetheless, because he himself piqued our curiosity again and again through the Fawā’id with his references to what he simply calls the “Nayrūz”. This solar calendar of Persian origin was used by Muslim pilots as the chronological reference for sailing seasons, as a complement to the lunar Hijri calendar they used in everyday life. In the Fawā’id, Nayrūz means simply “the first day of the solar year,” just like the contemporary cognate term, Nowruz.

But there are several kinds of Nayrūz mentioned: the Hindi, the Jalālī, the Arab… So we thought that Sulaymān al-Mahrī, the other luminary of Arab nautical literature, would help us clarify things, and we set about reading his brief Qilādat al-shumūs, the “Necklace of Suns”, where he lists five different calendars known to 15th century pilots: “lunar, solar, Byzantine, Coptic, and Persian.”

The little treatise itself is quite dry, a series of arithmetical formulas used to calculate the “uss”, “basic element” of each calendar. From what we have gathered so far, this has to do with calculating the relation between lunar phases and the beginning of the solar year reckoning, which naturally concerns the relation with the lunar Hijri calendar. There is much to be said about this remarkable occurrence of the perennial dynamics between sun and moon: the predicament of our pilots simply frames anew the old fundamental calendrical riddle, “how to account jointly for lunar and solar cycles, since as humans we rely on both luminaries?” “How to ‘marry’ sun and moon in the calendar for the sake of our science and cognition?”

But to leave on a lighter note for the festive days ahead, consider this instead: early modern Arab pilots, like their medieval forebears, rode the waves and lived their lives in a truly multipolar world, where even time-reckoning was far from uniform, and where several eras coexisted. When reaching lands of different cultures, they were quite practically time travelling, sometimes moving centuries back and forth. While the practical advantages of having world standards are undeniable, what an impoverishment that other eras have today become mere curiosities or exclusively liturgical in purpose. How many eras do we know about today? Today’s solstice must surely be a great occasion for giving them a thought. We wish you all good cheer at this start of new cycles! [JA]