15 December 2025

The Maimonidean Controversy, Part 2

European Jews were not accustomed to contemplating either Arabic philosophy or what they called "Greek wisdom," the works of Aristotle, Plato, etc. Those texts were only slowly transmitting across Europe in the 13th century. They were therefore unprepared for some of the conclusions that Maimonides (seen here as a statue in his hometown of Cordova) came to with his rationalistic-philosophical approach to questions of the divine.

One of the controversies was Maimonides' statement that since God created the laws of Nature, He would not violate them. Therefore, once a body starts to putrefy, bodily resurrection was not to be expected. Instead, there would be a spiritual resurrection, but the body remained corrupted. This did not sit well with some.

But Maimonides' blend of Aristotelianism with Jewish tradition, "reason versus revelation" so to speak, was becoming more widespread at the same time that Christian Europe was asserting itself on the Arabic/Muslim world via the Crusades and the effects of the Reconquista were being felt in the Iberian Peninsula. This was also right at the height of the Albigensian Crusade, with its desire to stamp out any deviation from "accepted religious policy" by any means possible. You had many groups all feeling threatened by "The Other," and wanting to take great lengths to prevent other doctrines from gaining ground.

This is also the time, in 1232, when Yonah Gerondi and others convinced secular (Christian) authorities to round up and burn Maimonides' work in Montpellier, causing the men to be condemned by followers of Maimonides and inspiring secular authorities to later burn several wagonloads of Talmud (and no doubt related Jewish documents).

By 1300, however, men like Thomas Aquinas and Duns Scotus read and quoted The Guide For the Perplexed. Aquinas was interested in using reason to prove the existence of God, and quoted Maimonides' Guide several times (although Aquinas misunderstood a lot of Maimonides, according to what I see here.)

Being quoted by an eminent theologian of the 14th century helped bring Maimonides into the mainstream without the threat if having his books burned. The influential "Rabbi of Spain," Shlomo ibn Aderet, who was dabbling in the Kabbalah, was more accepting of thoughts outside the mainstream and saw no reason why Maimonides' works ran counter to the collective body of Halakha, Jewish religious law. The modern view coincides with Aderet's, and Maimonides is considered a valuable voice in Jewish thought.

About Halakha: what does it contain? What besides the Torah and Talmud gets counted as important? Since I'm currently interested in this topic myself, I'm going to look into it and get back to you.

14 December 2025

The Maimonidean Controversy, Part 1

Recent posts have talked about different individual's attitude toward Maimonides and what they did about it—sometimes with radical consequences.

Besides studying all the known Jewish religious texts, Moses ben Maimon (1138 - 1204) was a rabbi, knew medicine (he was the personal physician of Saladin) and astronomy. He became well-known and liked in Egypt (he lived in Cairo for a time), but he also had some very vocal critics.

The chief issue is that he took a rationalist-philosophical approach to the world and came to conclusions that were contradictory to what many believed. A couple that I have mentioned before were:

•The power of prophecy does not require intervention by God. Any human being, through the application of logic and reason, study and meditation, has the potential to become a prophet.

•In a treatise on resurrection, he emphasizes that God would not violate the laws of Nature which He has created, and therefore any bodily resurrection would only be temporary; true resurrection to come is spiritual.

He really got under people's skin when he criticized the Geonim, the rabbinic scholars who took donations from sponsors. Maimonides felt they should learn a profession and support themselves, as he did.

After his death, his The Guide for the Perplexed was translated into Hebrew (he had been writing in Arabic). Jewish scholars around the Mediterranean who were familiar with Arabic philosophy could see and parse the influences on Maimonides' work, but when his work became accessible to European Jews it kicked off a new stage of controversy.

In the early13th century, European scholars were unfamiliar with concepts of science and philosophy. Aristotle's works were just being re-discovered in the West thanks to Arabic translations in Spain from the original Greek versions. Other works of philosophy were starting to spread because 1204 was not only Maimonides' death but also the Sack of Constantinople, which started bringing Greek treasures—including intellectual treasures—to the West.

I'll go into more about how the controversy heated up in Europe tomorrow. Meanwhile, you can read a little more about Maimonides and the intellectual evolution of Western Europe in my post on Scholasticism.

13 December 2025

Learning a Lesson

Yonah Gerondi had an Italian student in Barcelona named Hillel ben Samuel (c.1220 - c.1295) The grandson of a known Talmudic scholar, Hillel grew up to be a physician and Talmudic scholar himself. While practicing medicine in Rome, he became friends with Maestro Isaac Gajo, the pope's physician.

Hillel was strictly orthodox in his Judaism, proclaiming his absolute belief in the miracles outlined in the Torah and Talmud, despite some of these stories being considered more symbolic by other scholars. He wrote a book that covered the philosophic works of the time from Arabs, Christians, Jews, and Muslims.

He also translated some of the works of Thomas Aquinas into Hebrew, accepting Aquinas' idea of the soul's immortality. He referred to Aquinas as the "the Maimonides of his age."

Hillel had originally been opposed to Maimonides, but changed after he saw his teacher, Gerondi, change his attitude toward Maimonides. Gerondi had been opposed to Maimonides' rationalist approach to religious questions, and had caused the authorities of Paris to round up copies of Maimonides' works and burn them, specifically the Guide for the Perplexed. Gerondi regretted convincing the Christian leaders to take such a bold action against Jewish literature, especially when years later they burned all the copies they could find of the Talmud. Hillel saw Gerondi's regret, and how he radically hanged his attitude toward Maimonides.

Hillel moved to Forli in northern Italy when he was much older. While there he learned that a Tosafist (someone known for writing commentaries on the Talmud), a French Jew named Solomon Petit, was speaking out strongly against Maimonides. Aware of how Gerondi's anti-Maimonidean crusade turned out, Hillel addressed two long letters to his friend Isaac Gajo, explaining what had happened and asking him not to give any support to Petit's complaints.

What was the problem with Maimonides? What was the controversy about? I'll give you a taste of that tomorrow.

12 December 2025

Burning the Talmud

Yonah Gerondi, or Jonah ben Abraham Gerondi (c.1200 - 1263), was a 13th century rabbi from Catalonia in Spain. He was a cousin of Nachmanides and one of the teachers of Shlomo ibn Aderet.

He was part of a faction that was opposed to Maimonides, whose Guide for the Perplexed was very popular. The Guide's logical and philosophical examination of concepts such as whether God was corporeal or whether something could be created from nothing contradicted many earlier scholars.

Gerondi organized a victory over Maimonides' teaching by convincing the authorities in Paris to round up any copies of the Guide for the Perplexed and burn them. Unfortunately for Gerondi, this attack on the works of a fellow Jew inspired anger of local Jews against Gerondi. Some years later, on the same public spot where Maimonides' works had been burned, the authorities burned several wagonloads of the Talmud and other works.

Gerondi felt remorse, blaming himself for originally bringing Christian authorities into the philosophic debate between Jews. In the synagogue at Montpellier in France he proclaimed publicly his shame at fighting against Maimonides.

Vowing to do penance by traveling to Israel and prostrating himself on Maimonides' grave, he left France but was stopped at Barcelona and then in Toledo. He stayed in Toledo and became known as a great Talmudic scholar who also frequently quoted Maimonides. He died suddenly in 1263, some said because he never finished his vow to do penance in Israel.

His attitude toward Maimonides and the shift after the burning of the Talmud is told to us by his student, Hillel ben Samuel. Hillel was not only a Talmudic scholar but also a physician. Tomorrow I'll tell you how he learned his lesson from Gerondi's story.

11 December 2025

The Rabbi of Spain

Born in 1235 in Barcelona, Shlomo ben Avraham ibn Aderet became known as the Rabbi of Spain because of his reputation for knowledge and wisdom. He had famous teachers: Nachmanides and his cousin, Yonah Gerondi.

Aderet became a banker, but was an expert on the Talmud and was treated as the leader of Spanish Jewry. He was rabbi of the Barcelona Synagogue for 50 years. People came from all over to hear him lecture on the Talmud. His fame spread to the point that questions were sent to him from all over Europe and the Mediterranean. Three thousand of these questions and his responses still survive.

He was a great defender of Judaism from external and internal forces. When the Dominican Raymond Martini read the Talmud and found passages that he believed supported Christianity, he also found passages that he said blasphemed. Martini wrote a document condemning the Talmud. Aderet wrote a response to this document. On the other hand, when a Muslim attacked Christian priests for falsifying the Bible, Aderet refuted his statements.

Aderet cared about authenticity, and "pure Judaism." Although he defended Maimonides when he got into trouble with authorities for some of his interpetations, Aderet did not approve of Maimonides' philosophic-rationalistic approach that saw reason as the best tool in understanding the divine rather than faith. In fact, Aderet was part of the beth din (the rabbinical court of law) in Barcelona that forbade men younger then 25 from studying secular philosophy or natural science, lest they be led astray by worldly thinking. (They were allowed to study medicine.) He was quite adamant about avoiding being led astray, writing: 

In that city [Barcelona] are those who write iniquity about the Torah and if there would be a heretic writing books, they should be burnt as if they were the book of sorcerers.

Trying to enforce this ban created much hostility in his final years as rabbi. He was also sympathetic to those who wanted to study Kabbalah. but spoke out against people who took it to an extreme and considered themselves more than just men, namely people like Nissim ben Abraham of Avila and Abulafia.

Aderet died in 1310. Some of his students became famous in their own right. But I want to say something more about one of his teachers, Yonah Gerondi, who got involved in a religious controversy that led to an anti-jewish event I've mentioned before. I'll explain tomorrow.

10 December 2025

False Messiahs, Part 2

Yesterday we started looking at some of the predictions about the Jewish Messiah appearing in the 12th century. The 13th century had its own claimants as well. Abraham ben Samuel Abulafia was one.

Born in Aragon in 1240, he was taught the Torah and Talmud by his father after the family moved to Navarre. When Abulafia was 18, his father died, and the young man began wandering the world, eventually deciding to go to Israel and find the Ten Lost Tribes. Unfortunately, the Crusades had made a journey to Israel dangerous, so he returned to Europe, studied the Guide for the Perplexed of Maimonides, and started having visions.

He studied Kabbalah, and immersed himself in the Sefer Yetzirah, finding in it the path to perfection for a human being. In 1280 he went to Rome to convert Pope Nicholas III to Judaism. Hearing of his intention, the pope gave orders to burn the heretic as soon as he arrived. Before Abulafia reached Rome, however, he heard that Nicholas died of a stroke, so he returned to Messina where he was imprisoned for a month by the Order of Friars Minor.

In Messina he is reported to have declared himself a prophet and the Messiah, which angered the local Jewish congregation. A letter against Abulafia written by the influential Shlomo ben Aderet of Barcelona—who was making it his life's work to speak out against the rise of false Messiahs—helped put an end to Abulafia's career. Up until 1291 he was in Malta and writing his own works on meditation and symbolism, after which he disappears from records.

The other major "Messiah" of this century was Nissim ben Abraham, whom we discussed in the story of Abner of Burgos.

It is interesting that there was enough concern about false Messiahs that Shlomo ben Aderet had a career about denouncing and disproving them. Let's take a look at Shlomo next, the "Rabbi of Spain."

(The illustration is from William Holman Hunt's 1860 "The Finding of the Saviour in the Temple.")

09 December 2025

False Messiahs, Part 1

Yesterday's post explained how Abner of Burgos' conversion to Christianity from Judaism may have started with doubts after treating patients who were distraught after a promised Jewish Messiah failed to appear.

As it turns out, there were more than a couple claims about the appearance of the Messiah. The 2nd, 5th, 7th, and 8th centuries had their share. In the Middle Ages, there were quite a few, some documented, some not so much, like the one reported to have been simply killed by the French in 1087.

A teacher in Morocco, Moses ben Abraham Dar'ī, believed a Messiah would appear at Passover in 1127 to specifically free the Jews in the territories controlled by the Almoravid dynasty.

Menaḥem ben Solomon was born in Iraq. Growing up he studied the Torah and Talmud and, calling himself David Alroy or David el-David (meaning "David son of King/David") claimed to be the Messiah, calling on Jews to rise up against their caliph and then go to Jerusalem where they would free it from the Muslims. (Yes, a Jewish crusade in the 1160s!)

Stories of his results differ, but Benjamin of Tudela wrote that the sultan had David brought to him, asked him "Are you the king of the Jews?" to which David replied "I am." whereupon he was thrown into prison. Three days later he "rose again"; that is, he miraculously appeared in the midst of the sultan's council, then evaded arrest by turning invisible, making the 10-day journey back to his native town, Amadiya, in one day. The sultan threatened to put all Jews in his domain to death unless David surrendered. The governor of Amadiya bribed David's father-in-law to kill David.

Maimonides in his Iggeret Teman (Epistle to Yemen) tells the story of a Yemenite Messiah. Born in Fez in Morocco, he grew up at a time when the Muslims were trying to get all Jews to convert. The Yemenite Messiah claimed the troubles this caused were a sign that a Messiah would soon appear to liberate them. He started preaching that property should be distributed to the poor and people should start repenting for their sins. After a year of becoming a public nuisance the Muslims arrested him. He himself suggested that they kill him so he could prove himself by returning to life. He was beheaded, and his story ends there.

I'll tell you a more tomorrow.

08 December 2025

Abner of Burgos, Converso

Abner of Burgos (c.1270 – c.1347) converted to Christianity from Judaism around 1320, taking on the name Alfonso of Valladolid or "Master Alfonso." He was well into adulthood, so his conversion was not a rebellion against his parents' culture, nor was it a young man's quest for something "different," nor was it forced upon him by an oppressive Christian government. So what happened?

The Jewish belief in a messiah gave rise to many claims over the centuries that he was imminent. In Avila, in central Spain, a Jew named Nissim ben Abraham actively preached that the messiah would appear in 1295 on the last day of the month of Tammuz (which can fall in late June or early July). Nissim was said to be a simple man who was inspired by an angel and wrote a mystic work, "The Wonder of Wisdom."

Many were convinced by Nissim, and they eagerly awaited the messiah. Like predictions of the Second Coming or of the End of the World, no messiah appeared. What they experienced, however, was a rain of crosses that stuck to their clothing (so they described to Abner). The disappointment and depression that followed among Nissim's adherents was profound.

Abner, a scholar of the Bible and the Talmud as well as a doctor, found himself being turned to by these disappointed people, treating them and trying to assuage their grief. Curiously, his discussions with these people about the lack of a messiah and their report of the appearance of the Christian symbol made him think "outside the box" about Judaism and its promises.

In a post-conversion work by Abner, Moreh tsedeḳ ("Teacher of righteousness"), he described how some 25 years after Avila he had a dream/revelation of a man who told him to become a "teacher of righteousness." About three years later he had the same dream, but this time noticed that the man had crosses on his clothes. This was his tipping point: he chose to embrace Christianity. He became a Neo-Platonic Christian and wrote treatises against Judaism. He believed that his version of Christianity was superior to others' and to Judaism. He preached that conversion to Christianity was the only way for Jews to get out of their perpetual Exile.

He was appointed sacristan of the collegiate church of Valladolid. This made some Jews accuse him of converting for material gain. What they did not understand, however, was that a sacristan was far from a lucrative position. He wrote extensive works (not all extant, or available in English) supporting conversion of Jews. He also debated rabbis. His arguments to King Alfonso XI of Castile that a Jewish prayer, the Birkat haMinim, blasphemed the Christian God and cursed Christians, led to the prayers being declared forbidden as off February 1336. The Birkat declares a curse on all heretics (so he had an ironic point, I guess).

We have his works, but no record of his death. 1347 was the last known record of him publishing. It is possible that he was a victim of the Black Death.

There were a few claims of a Jewish Messiah in the Middle Ages (and earlier and later). We'll look at some of them tomorrow.

07 December 2025

The Christian Kabbalah

Scholars and philosophers of the later Middle Ages became interested in the mysticism found in the Jewish Kabbalah and tried to blend it with Christian concepts of the divine.

Ramon Llull (c.1232–1316), who also wrote of worldly affairs like knighthood, was one of the first known Christians to look at Kabbalah, although his study of it was mostly to develop ways to debate Jews and influence conversion to Christianity. His interest got him in trouble because the concepts he was talking about attracted the attention of the Inquisition.

The conversion of Spanish Jews did bring Kabbalistic concepts to Christian theology, especially in Spain prior to 1492. One prominent converso was Abner of Burgos (c.1270 – c.1347), a Bible and Talmud scholar who had a dream of crosses after he developed religious doubts because of a failed Messianic movement in 1295. He embraced and used Jewish sources to try to prove the validity of Christianity.

Another converso was Pablo/Paulus de Heredia (c.1405), who wrote an "Epistle of Secrets" which is considered the first true work of Christian Kabbalah. Not the scholar that Abner was, Pablo's work misquotes Kabbalah sources and "quotes" sources that are non-existent.

A Christian who adopted Kabbalistic ideas was Giovanni Pico della Mirandola (1463–1494), a student of Marsilius Ficino. (The illustration shows Pico in the center with Ficino in red next to him.) Kabbalah was introduced to him by another tutor, Rabbi Johanan Alemanno, whose idea was that the study of magic was the ultimate goal and expression of intellectual and spiritual mastery. Pico became convinced that the Kabbalah was necessary to understand the world and the divine, and had a Jewish convert translate the entire body of kabbalistic literature into Latin for him (now being published in its entirety). Pico's "900 Theses" became a foundation of Western esotericism.

So how exactly does a lifelong Jew decide to convert to Christianity (I mean, when not being forced)? Let's examine Abner of Burgos' personal journey tomorrow, and whether he did it for financial gain.

06 December 2025

Jewish Mysticism

The mention of Jewish mysticism likely evokes the Kabbalah, but there were other forms. I suppose you could argue that it begins with Adam, the first man, if the theory that the Sefer Yetzirah was written by Adam were true (but let's look at other options).

In fact, there were many philosophical trends prior to the Common Era (like Prophetic Judaism and Apocalyptic Judaism). The Sefer Yetzirah is judged to have inspired/affected Jewish mysticism in 200-600CE with its ideas on the formation of the world using the Hebrew alphabet and 10 sefirot.

The 11th through 13th centuries saw a rise in named scholars producing works that tried to explain the universe and the relationship of Man to God. This is where we find Isaac Israeli ben Solomon developing Jewish Neoplatonism, along with men like Solomon ibn Gabirol and Abraham ibn Ezra and Maimonides.

Neoplatonism was an attempt to "modernize" the works of Plato—considered a primary utility on intellectual thought but needing more work as new ideas came about in the centuries following his era—by people like John Eriugena and many others. One of its common themes was monism, the idea that all reality c an be tied to and derived from a single principle.

Many of the Jewish scholars promoting mysticism were in Spain, where Muslims had taken over and brought with them Arabic-language versions of texts from Greek philosophers not yet available to the Latin West. Jewish mysticism flourished in Spain until 1492 and the Alhambra Decree that expelled all Jews from Spain.

One of the features of Jewish mysticism we find in the Sefer Yetzirah and in the Kabbalah is the development of the 10 sefirot: the 10 facets or dimensions of the inner self.

  1. Keter/Ayin (nothingness),  
  2. Hokhma (wisdom)  
  3. Binah (understanding)  
  4. Hesed (Kindness) 
  5. Gevurah (Discipline) 
  6. Tiferet (Glory) 
  7. Netzah (Victory) 
  8. Hod (Splendor) 
  9. Yesod (Foundation) 
  10. Shekhinah (Divine Presence)

The Sefer Yetzirah was the first work that listed 10 sefirot, but the tenth was called Malkut, which means "Kingdom" or "Queenship." (I am sure that there are countless pages written about why one over the other would be used.) In both the Sefer and Kabbalah the tenth of the sefirot refers to the point where the divine manifests in the real world. That is why (see the illustration) it appears at the bottom of the diagram, because despite its name it is the "lowest point" on the scale, being attached to the material world.

So what about Christian philosophers? What did they think about the Kabbalah? Well, some of them adopted some concepts from Kabbalah and Jewish mysticism. Let's talk about how that worked next time.

05 December 2025

The Sefer Yetzirah

Technically, the title of this post is the same as yesterday's, because Sefer Yetzirah translates as "The Book of Formation." Its author is unknown, its date of composition is widely debated, but it has been studied and annotated more than almost any other work besides the Bible (by scholars such as Nachmanides), and its influence on later Kabbalah was profound.

While there are older Jewish mystical traditions, Sefer Yetzirah is the first book of what might be called proto-Kabbalah, the school of Jewish mysticism that emerged in the 13th century. Sefer Yetzirah has its own sacred structures and ways of understanding the world that differ in significant ways from the kabbalistic understanding, but many of its concepts significantly influenced later Jewish mystical tradition and practice. [source]

It primarily seems to be a linguistic work, because it claims the Hebrew alphabet is the key to understanding how the universe was created. It even distinguishes how letters and words are formed by the mouth:

In contrast to the Jewish grammarians, who assumed a special mode of articulation for each of the five groups of sounds, the "Sefer Yeẓirah" says that no sound can be produced without the tongue, to which the other organs of speech merely lend assistance. Hence the formation of the letters is described as follows:  with the tip of the tongue and the throat;  between the lips and the tip of the tongue;  in the middle ([?]) of the tongue;  by the tip of the tongue; and by the tongue, which lies flat and stretched, and by the teeth (ii. 3). The letters are distinguished, moreover, by the intensity of the sound necessary to produce them, and are accordingly divided ... [Jewish Encyclopedia]

The illustration above (a poster available here) shows each of the letters and explains its importance according to the Sefer

And the letters show how they connect to the creation of the universe:

The linguistic theories of the author of the "Sefer Yeẓirah" are an integral component of his philosophy, its other parts being astrological and Gnostic cosmogony. The three letters are not only the three "mothers" from which the other letters of the alphabet are formed, but they are also symbolical figures for the three primordial elements, the substances which underlie all existence. The mute מ is the symbol of the water in which the mute fish live; the hissing ש corresponds to the hissing fire; and the airy א represents the air; while as the air occupies a middle position between the fire which reaches upward and the water which tends downward, so the א is placed between the mute מ and the hissing ש. [Jewish Encyclopedia]

The "32 paths of wisdom" that the Sefer Yetzirah claims God used to create the universe are the 22 letters of the Hebrew alphabet and the ten sefirot, later referred to as ten emanations or attributes of God. These sefirot are crucial to later Kabbalah and Jewish mysticism. Let's next take a look at how Jewish mysticism developed.

04 December 2025

The Book of Formation

There is a much-studied document in Jewish literature whose origin is unknown. It has been considered the work of a 1st-century Rabbi Akiva, or the first man Adam, or the patriarch Abraham. The Jewish Encyclopedia claims it is more likely a work of the 3rd or 4th century based on its form of Jewish gnosis. It is the Sefer Yetzirah, sometimes called the "Book of Creation" but more accurately the "Book of Formation."

Not only is its origin a topic for debate, so is its purpose. It has been considered to be a mystical work about the Kabbalah, an explanation of how the universe came to be, and a work about linguistic theory. Each of these theories can be supported by its opening statement:

By thirty-two mysterious paths of wisdom Yah has engraved [all things], [who is] the Lord of hosts, the God of Israel, the living God, the Almighty God, He that is uplifted and exalted, He that Dwells forever, and whose Name is holy; having created His world by three [derivatives] of [the Hebrew root-word] sefar : namely, sefer (a book), sefor (a count) and sippur (a story), along with ten calibrations of empty space and twenty-two letters [of the Hebrew alphabet], [of which] three are principal [letters] (i.e. א מ ש‎), seven are double-sounding [consonants] (i.e. בג"ד כפר"ת‎) and twelve are ordinary [letters] (i.e. ה ו ז ח ט י ל נ ס ע צ ק‎).

(This idea, that the Hebrew alphabet is the guide to God and the universe, found new life in the Modern Era in something called the Bible Code.)

There are different versions of it extant that have been annotated by different scholars. One shorter version annotated by Dunash ibn Tamim, a pupil of Isaac Judaeus, argues that Hebrew was the original universal language and Arabic is derived from it. He states:

If God assists me and prolongs my life, I shall complete the work in which I have stated that Hebrew is the original tongue of mankind and older than the Arabic; furthermore, the book will show the relationship of the two languages, and that every pure word in the Arabic can be found in the Hebrew; that the Hebrew is a purified Arabic; and that the names of certain things are identical in both languages.

A bold claim. The Sefer Yetzirah is the subject of almost as much speculation and annotation as the Bible. We'll continue our exploration of it tomorrow.

03 December 2025

Isaac Judaeus

An Andalusian Arab named Ibn Juljul wrote Ṭabaqāt al-aṭibbā’ w’al-hukamā’ ("Generations of Physicians and Wise Men") in the late 900s. It is one of the only sources for biographies of several early scholars, philosophers, and doctors. In it we learn details about the life and career of Isaac Israeli ben Solomon, who is sometimes called simply Isaac Judaeus.

He was born in Cairo and became known as an oculist (we've talked about medieval eye treatment before).  About 904 he became the court physician to Prince Abu Mudhar Ziyadat Allah III in Kairouan, capital of Tunisia. He studied general medicine while there.

After the death of Ziyadat in 909, Isaac became doctor to Caliph 'Ubaid Allah al-Mahdi, the founder of the Fatimid dynasty. The caliph enjoyed the witty repartee of his Jewish physician. Isaac began lecturing on medicine, and many people came to hear him speak as his fame spread. He continued to learn, studying astronomy, mathematics, medicine, and natural history.

He wrote medical manuals in Arabic which, in the Arabic-speaking world, were considered gems, but were unknown in Western Europe. The 12th century saw translators in Toledo striving to make many works available to a wider audience. Gerard of Cremona translated Isaac's Liber de Definitionibus (Book of Definitions) and Liber Elementorum (Book on the Elements) into Latin. Christian scholars started noticing his work, such as Albertus Magnus, Aquinas, Roger Bacon, Nicholas of Cusa, and Vincent de Beauvais.

One of his works dealt with the urinary tract, which I covered a few years ago.

The years of his life are given as different dates according to the source. Encyclopedia Britannica says born 832/855, Egypt—died 932/955) and that he lived more than 100 years. His death has been declared as 932, 940, 942, 950, and 955.

One of his pupils, Dunash ibn Tamim, wrote a commentary on a work of Jewish mysticism that quotes Isaac so extensively that later scholars thought it was written by Isaac himself. Dunash and this work, the Sefer Yetzirah, will be our next line of topics.

02 December 2025

Gilbertus Anglicus

I've talked before about John of Gaddesden, a late-13th-century doctor who wrote a compendium of medical knowledge. A little before him was another who created an encyclopedic work about what was known at the time of medicine and surgery.

His name was Gilbertus Anglicus (c.1180 - c.1250), called so because he was born in England, although after some initial education in his home country he went to Europe to study, particularly at the Salerno medical school. He actually returned to England for a time to assist a bishop, but that bishop died in 1205 and Gilbertus went back to Europe.

After 1230, he produced a seven-volume work in Latin called Compendium Medicinae. This work was copied and distributed as one of the foundational works of medical education for centuries (along with Gaddesden's). It was translated into Middle English in the early 1400s. It first saw formal print in 1510 with further editions, one as late as 1608. Chaucer includes him in the Canterbury Tales as one of the great physicians.

Among its seven volumes was a section on gynecology that was sometimes circulated separately as The Sickness of Women. Later it was called The Sickness of Women 2 after having a different author's work added. These became even more widely distributed than the Trotula.

One of the aspects that made Gilbertus' Compendium so valued was its inclusion of the knowledge of so many others. Pythagoras, Hippocrates, Plato, Aristotle, Galen are there, of course, but also Avicenna and Averroes, Macrobius, Boethius, several Arabians, Isaac Judaeus, and the Salernian writers.

Isaac Judaeus was mentioned briefly here regarding Charlemagne and an elephant, and I'd like to tell you more about him, starting tomorrow. Isaac, that is, not the elephant.

01 December 2025

Medieval Dentistry

What you are looking at here is a "pelican," so-called because it resembles a pelican's beak. It was used to extract teeth and tools like it are believed to have been in use since about 1200.

Although the biggest danger to healthy teeth these days is sugar, and sugar was not found in many diets until about 1400, cavities, toothache, abscesses, and other dental problems could arise. Consequently, the Middle Ages developed ways to deal with them.

Food buildup on teeth was rubbed or brushed away by the use of rough linen cloth or twigs frayed at the end. Other substances applied to teeth to help clean them could include ground sage and salt, or a mix of pepper, salt, and mint (after which you were advised to swallow the stuff). Another recommended tooth cleaner was the charcoal made from burning the woody part of the rosemary plant.

Having sweet breath was desirable, and methods to deal with halitosis included mouthwashes of vinegar or wine, sometimes with herbs steeped in them. Fennel seeds or parsley or cloves could be carried around and chewed in case the need arose to sweeten one's breath on the fly.

Still, daily wear and tear occurred on the teeth. Stoneground bread sometimes had grit that could wear away at the enamel, leading to cavities and tooth loss. When the pain became too much, a trip to the barber-surgeon was necessary. By 1210, in France there was guild of people who specialized in dentistry. They called themselves "barbers," and tried to regulate the practice. France made royal decrees in 1400 to ensure that those performing dentistry had the proper training.

Books of medicine did not neglect teeth. Trotula had a solution for woman with black teeth:

… take walnut shells well cleaned of the interior rind, which is green, and … rub the teeth three times a day, and when they have been well rubbed … wash the mouth with warm wine, and with salt mixed in if desired.

She had a more elaborate recipe:

Take burnt white marble and burnt date pits, and white natron, a red tile, salt, and pumice. From all of these make a powder in which damp wool has been wrapped in a fine linen cloth. Rub the teeth inside and out.

After this rinse with wine again, then wipe the teeth with a new white cloth (have to get ride of the wine stains, after all!).

The advice to swallow the pepper and salt mixture came from Gilbertus Anglicus, who wrote a Compendium of Medicine. Let's talk about him and it tomorrow.