**Abraham bar Hiyya** was a Spanish Jewish mathematician and astronomer. He wrote the first book to introduce Islamic algebra to Europe.

- In the Hebrew of his time 'Ha-Nasi' meant 'the leader' but he is also known by the Latin name Savasorda which comes from his 'job description' showing that he held an official position in the administration in Barcelona.
- Abraham bar Hiyya is famed for his book Hibbur ha-Meshihah ve-ha-Tishboret (Treatise on Measurement and Calculation), translated into Latin by Plato of Tivoli as Liber embadorum in 1145.
- Rather strangely, however, 1145 was also the year that al-Khwarizmi's algebra book was translated by Robert of Chester so Abraham bar Hiyya's work was rapidly joined by a second text giving the complete solution to the general quadratic equation.
- It is interesting to see the areas of mathematics and the mathematicians with which Abraham was familiar.
- Abraham had also studied some of the important works on algebra by Arab mathematicians, in particular al-Khwarizmi and al-Karaji.
- Among other texts written by Abraham bar Hiyya was Yesod ha-Tebunah u-Migdal ha-Emunah (The Foundation of Understanding and the Tower of Faith).
- Abraham also wrote a number of texts on astronomy; in particular he wrote on the form of the Earth and the calculation of the paths of the stars on the celestial sphere.
- His book Tables of the Prince refers to the tables of al-Battani while Abraham's treatise Sefer ha-Ibbur (Book of Intercalation), written in 1122-23, is the first Hebrew work devoted exclusively to a study of the calendar.
- In the philosophical treatise Hegyon ha-Nefesh ha-Azuva (Meditation of the Sad Soul) Abraham deals with the nature of good and evil and ethics.
- Megillat ha-Megalleh (Scroll of the Revealer) outlines Abraham's view of history based on astrology.
- Perhaps one of the most important features of Abraham bar Hiyya's work is the fact that it appears to have stimulated an interest in Arabic mathematics and, together with the work of Abraham ibn Ezra, marks the beginning of Hebrew scholarly study of mathematics.
- This movement occurred after the original works by Abraham bar Hiyya and Abraham ibn Ezra became available to a wide readership.
- It is rather difficult to place Abraham bar Hiyya in the development of mathematics since in most respects he did not fit nicely into one culture but spanned several.
- He spent most of his life in Barcelona, an area of both Arab and Christian learning, and was active in translating the masterpieces of Arab science.

Born 1070, Barcelona (now Spain). Died 1136, Provence, France.

View full biography at MacTutor

Algebra, Astronomy, Origin Spain

Epochs: 1

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive