Tag Archives: Barcelona

Jew of the Week: Avraham bar Chiya haNasi

The Rabbi Who Discovered the Quadratic Formula

Avraham bar Chiya (c. 1070-1145) was born in Barcelona to a Sephardic Jewish family. It appears that his family was persecuted by its Christian rulers, so they fled to the neighbouring Arab kingdom of Zaragoza. Bar Chiya came from a long line of rabbis, and was also extensively trained in science, math, and astronomy. Famed for his wisdom, he became the court astronomer of Al-Musta’in II. Eventually, he was appointed minister of police and given the title sahib al-shurtah, “city governor”. This is why he was known in the Jewish community as HaNasi, “the prince” or “the president”. Al-Musta’in II was unable to defend his domain from the Christians, who soon took over. Bar Chiya moved to southern France for a while and lived in Narbonne and Provence. There he composed some of the most important scientific texts of the Medieval era. He translated a number of Arabic works into Latin, opening their study for Europeans, and played a key role in introducing the Hindu numerals we use today (by way of Arabia) to Europe, and thus to the rest of the world. Bar Chiya also synthesized ancient Greek wisdom with contemporary Arabic knowledge, and published new discoveries in number theory, arithmetic, geometry, optics, astronomy, and music theory. His Treatise on Measurement and Calculation inspired later greats like Plato of Tivoli and the world-famous Fibonacci. Meanwhile, Bar Chiya also served as the chief rabbi of the Jewish communities he presided over, and composed two important Jewish commentaries and texts. He is credited with being the first person to write a scientific book in Hebrew, and played an instrumental role in the development of the Hebrew language. His disciples included both Jews and non-Jews, among them the great Rabbi Abraham ibn Ezra, and the Flemish astronomer Rudolf of Bruges. The first historical appearance of the quadratic equation (with a complete solution of x2 – ax + b = c) appears in one of Bar Chiya’s works! He is also referenced in many philosophical works as “Abraham Judaeus”. All in all, his impact on the development of science, mathematics, and human history is unparalleled.

Jew of the Week Turns 10 Years Old Today!

What I Learned from 10 Years of Writing Jew of the Week

Words of the Week

The mind of man plans his way, but God directs his steps.
King Solomon (Proverbs 16:9)

Jew of the Week: Don Fernando de Aguilar

Shana Tova v’Metuka!

Don Fernando de Aguilar on the cover of a children’s book

Don Fernando de Aguilar (c. 1500) When Spain expelled its Jews in 1492, some chose to stay behind and convert superficially to Christianity, practicing their Judaism in secret. One of these Conversos (or Marranos) was Don Fernando de Aguilar, who also happened to be the conductor of the Royal Orchestra in Barcelona. Despite the fact that Judaism was outlawed in Spain (until 1967, in fact) de Aguilar organized secret prayer services in the basement of Don Manuel’s leather shop. But there was one mitzvah they could never keep: hearing the shofar. After many years of longing for the sounds of the shofar, Don Fernando came up with a clever idea. He wrote a concert featuring the “melodies of the world”, set to play in Barcelona over the High Holiday season. Fernando expertly weaved the shofar into his opus, with packed crowds of hidden Jews listening in, along with the fooled Inquisitors. Rabbi Eliyahu Kitov writes: “It was said that no one had ever been more successful in confusing Satan on Rosh HaShanah than was Don Aguilar.”

Words of the Week

Three books are opened on Rosh Hashanah: The righteous are inscribed in the book of life; the wicked are inscribed in the book of death, and the judgment of the intermediates hangs in balance until Yom Kippur…
– Talmud, Rosh HaShana 16b