al-Farghani's Accomplishments

Despite the potentially reputation-damaging error in calculation made by al-Farghani in the case of a canal, he is better known for other accomplishments.

Abū al-ʿAbbās Aḥmad ibn Muḥammad ibn Kathīr al-Farghānī (c.800 - 870) was known as Alfraganus in Western Europe (see illustration, from a 1493 astronomical work). He was described as Arab and as Persian; there is a suggestion that his name comes from being born in Farghana in Uzbekistan.

His best-known work was Kitāb fī Jawāmiʿ ʿIlm al-Nujūm (Elements of astronomy on the celestial motions), a summary of Ptolemey's astronomical Almagest with revised calculations. He concentrated less on the mathematics and more on explaining the concepts in ways that were easy to understand. This work reached the West in translations by John of Seville and Gerard of Cremona. Dante's knowledge of astronomy came from al-Farghani.

One of his first recorded acts is being involved in a team that calculated the diameter of the Earth. This work influenced Columbus in his voyage across the Atlantic. Columbus, however, misunderstood the translation of al-Farghani's use of "mile." Columbus assumed al-Farghani was using the 4856-foot Roman mile; actually, al-Farghani used the 7091-foot Arabic mile. Columbus thought the diameter of the Earth was smaller.

In Cairo, al-Farghani wrote a treatise on the astrolabe earlier than al-Ashraf Umar II and Abd al-Rahman al-Sufi. Also while in Cairo he supervised the New Nilometer. The Nilometer, as you might guess, was designed to measure the height and clarity of the water of the Nile River.

The annual flooding of the Nile was crucial to Egypt's agricultural cycle, but it was unpredictable. Too heavy a flood was destructive; too light could lead to famine. Knowing what was coming was important. Nilometers come in different designs, but the simplest was a vertical column submerged in the river with markings to denote height of the water. Later, more elaborate versions involved shafts with steps that led down. Noting the height and comparing it to previous years helped predict whether the crops would be successful.

Speaking of flooding...next I want to tell you about a flood that killed thousands in more than one country. See you tomorrow.

Isaac Israeli ben Solomon

Some of the works translated at Toledo by our old friend Gerard of Cremona were the Book of Definitions and the Book of Elements into Latin from Arabic. Written by Isaac Israeli ben Solomon (alias Isaac Israeli the Elder, alias Isaac Judaeus), sometimes known as Isaac the Jew, they and his other works became standard works in medicine at Salerno.

Isaac Israeli ben Solomon was born in Egypt around 832CE. Growing up in Cairo, he became known as a skilled oculist (illustration is from an Arabic manuscript on oculism, showing the parts of the eye). About 904CE he was made court physician to Emir Ziyadat Allah III of Ifriqya (and I really should talk about him and there in the near future). A few years later he traveled to Kairouan, Tunisia and studied under a famous Arab physician, then became the doctor to 'Ubaid Allah al-Mahdi, who founded the Fatimid dynasty. al-Mahdi found Israel charming and witty.

In Kairouan he started writing his treatises, which were considered "more valuable than gems," and giving popular lectures on medicine and other topics in science. All his treatises were written in Arabic. Besides the ones mentioned above, they also include The Book on Fevers, a work on food and remedies called Universal Diet, and more. He also wrote books on philosophy, metaphysics, logic, a commentary on Genesis, and a treatise on the difference between the spirit and the soul. The Latin translations of many of these were quoted by Albertus Magnus, Aquinas, Roger Bacon, Nicholas of Cusa, and others.

Next I want to delve into one of his works specifically. I don't think I've ever indulged in what they call "dad jokes," but let me just say "urine for a treat."

The Toledo School of Translators

In the beginning of the 12th century, European science lagged behind Arabic scholarship, in many ways because early Greek texts had not made the transition to Western Europe, but were accessible by Arabic scholars in the Eastern Mediterranean, particularly their association with the Byzantine Empire. In the mid 12th century, the Archbishop of Toledo, a French Benedictine named Francis Raymond de Sauvetât (fl.1125-52), established the Toledo School of Translators at the Cathedral of Toledo to correct this lack.

The archbishop assembled a team that included Jewish scholars, Madrasah teachers, Cluniac monks, and Mozarabic Toledans.

The goal was not just to make Arabic learning available to the Latin-speaking west. Arabic texts were translated also into Hebrew and Ladino (Judaeo-Spanish). Examples are works by Maimonides, Ibn Khaldun (considered the originator of studies that would evolve into sociology and economics), and the physician Constantine the African.

The school was well-organized, and as a result we are aware of many of the translators who worked there. Gerard of Cremona was not the only noteworthy translator. John of Seville (fl.1133-53) was one of the chief translators into Castilian, working closely with Dominicus Gundissalinus, the first appointed director of the school.

The importance of Toledo for Western European scholarship cannot be underestimated. The University of Paris was the seat of the Condemnations of Paris: between 1210 and 1277, they were enacted to restrict teaching that were considered heretical. Without Toledo, who knows how long it might have taken for Europe to gain access to so much knowledge?

The school had two chief periods of activity. Tomorrow I'll talk about the second, and the importance of Castilian.

Gerard of Cremona x 2

Gerard of Cremona (1114-1187CE) was an important translator of Arabic texts into Latin. Born in Cremona in northern Italy, he went to Toledo in the Kingdom of Castile because he desired to learn more about Ptolemy. Why did an Italian travel to Spain to learn about a Greek? Because Ptolemy's writings, although the man and his importance were known to Europe, were not available except in Arabic translations from the Greek.

Why Toledo? We'll delve into that more deeply tomorrow. For now, know that Gerard learned Arabic sufficiently that he not only translated Ptolemy's Almagest, the definitive work on astronomy until it was replace by Copernicus, but also he is credited with translating a total of 87 Arabic works.

Many of them were Arabic translations of Greek originals. Gerard's work made available to Latin readers works by Archimedes, Aristotle, Euclid's Elements of Geometry, and Arabic works on algebra and astronomy. He also edited the Tables of Toledo, a compilation of astronomical data.

There was a second Gerard of Cremona, however, and some of the 87 works attributed to Gerard might have been translated by Gerard, if you follow. This second Gerard was working in the 13th century, and seems to be the translator of medical works, whereas the first concentrated on astronomy and science. Roger Bacon's access to Al-Kindi's work, which would have been after 1240, is likely to be due to the second Gerard. Modern scholarship on the work of Gerard points out that many of the words he uses in his Latin translations are still used today; diaphragm, orbit and sagittal are examples. (To be fair, some of the modern scholarship also suggests that his translations look like the work of a hurried graduate student.)

But back to Toledo. In the 12th and 13th centuries, there was a robust Toledo School of Translators. I'll tell you about it tomorrow.