Rabbi Abraham ben Samuel Zacuto

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Rabbi Abraham ben Samuel Zacuto, III

Also Known As: "Abraham Zacutto"
Birthplace: Salamanca, CL, Spain
Death: 1515 (62-63)
Damascus, Dimashq, Syria (Syrian Arab Republic)
Immediate Family:

Son of Rabbi Samuel ben Abraham Zacuto and Mrs. Samuel Zacuto
Husband of Mrs. Abraham Zacuto
Father of Samuel Abraham Zacuto

Occupation: Astronomer Mathematician, Historian, Rabbi
Managed by: Pam Karp on Sabbatical till Sept...
Last Updated:

About Rabbi Abraham ben Samuel Zacuto

Abraham Zacuto (Hebrew: אברהם זכות, Portuguese: Abraão ben Samuel Zacuto) (c. 1450 – c. 1510) Spanish astronomer mathematician, and historian; born at Salamanca about 1450; died in Turkey after 1510.

An astronomer of wide-spread reputation, he was appointed professor at the university of his native city, and later at that of Saragossa. After the Spanish exile, Zacuto settled at Lisbon, where he was soon appointed court astronomer and historiographer to John II. He retained his office under D. Manuel, and in this capacity he was consulted by the king regarding the practicability of the projected expedition of Vasco da Gama, which he approved and encouraged. The ships fitted out for the expedition were provided with Zacuto's newly perfected astrolabe, which was the first to be made of iron instead of wood.

The great services rendered by Zacuto did not protect him, however, from the persecutions inaugurated by Manuel at the instigation of Ferdinand and Isabella; and he and his son Samuel were forced to seek safety in flight. After an eventful voyage in which he was twice taken prisoner, Zacuto reached Tunis, where he lived until the Spanish invasion, when he fled to Turkey, residing there for the remainder of his life.

In 1504, during his sojourn at Tunis, he wrote a chronological history of the Jews from the Creation to 1500, making constant reference to Jewish literature, and entitling his book "Sefer ha-Yuḥasin." In this work Zacuto gives an account of the oral law as transmitted from Moses through the elders, prophets, sages, and the like, and also records the acts and monuments of the kings of Israel, as well as of some of the surrounding nations. In like manner space is given to the Babylonian captivity, the events which occurred during the period of the Second Temple, the characteristics of that period, the princes of the Captivity, and the rectors of the academies of Sura and Pumbedita. Although the author was far from discriminating as to his sources, and thus fell into many errors, his work is of great value to the student of Jewish literary history.

The "Sefer ha-Yuḥasin" was edited by Samuel Shalom with many omissions and additions of his own (Constantinople, 1566), and was reprinted at Cracow in 1581, at Amsterdam in 1717, and at Königsberg in 1857, while a complete edition was published by Filipowski in London in 1857. In 1473, while still at Salamanca, Zacuto wrote his "Bi'ur Luḥot," which was published in a Latin translation under the title "Almanach Perpetuum" by Joseph Vecinho (Leiria, 1496), who also rendered it into Spanish and appended it to his "She'erit Yosef." Zacuto was likewise the author of three other works: "Sefer Tekunat Zakkut," an astronomical work which is believed to be still extant in manuscript (see "Ha-Shaḥar," i., No. 12); "Arba'im la-Binah," a treatise on astrology; and "Hosafot le-Sefer ha-'Aruk," a rabbinic Aramaic lexicon, of which an account is given by A. Geiger in "Z. D. M. G." xii. 144.

Read more: http://www.jewishencyclopedia.com/view.jsp?artid=7&letter=Z&search=Zacuto#ixzz0giadUXnv


Abraham Zacuto (Hebrew: אברהם זכות, Portuguese: Abraão ben Samuel Zacuto) (c. 1450 – c. 1510) was a Sephardi Jew astronomer, astrologer, mathematician and historian who served as Royal Astronomer in the 15th century to King John II of Portugal. The crater Zagut on the Moon is named after him.


Zacuto was born in Salamanca, Spain circa 1450. He studied astronomy at the University of Salamanca and taught there as well. He later was for a time teacher of astronomy at the universities of Zaragoza and then Cartagena. He was versed in Jewish Law, and was rabbi of his community.

With the general expulsion of the Jews from Spain in 1492, Zacuto took refuge in Lisbon, Portugal. Already famous in academic circles, he was invited to court and nominated Royal Astronomer and Historian by King João II, a position which he held until the early reign of Manuel I. He was consulted by the King on the possibility of a sea route to India, a project which he supported and encouraged. Zacuto would be one of the few who managed to flee Portugal during the forced conversions and prohibitions of departure that Manuel I enacted, in order to keep the Jews in Portugal as nominal Christians for foreign policy reasons (see History of the Jews in Portugal).

He died in the Ottoman Empire, to where he had escaped, ca. 1510.


Zacuto perfected the astrolabe, which only then became an instrument of precision, and he was the author of the highly accurate Almanach Perpetuum that were used by ship captains to determine the position of their Portuguese caravels in high seas, through calculations on data acquired with an astrolabe. His contributions were undoubtedly valuable in saving the lives of Portuguese seamen, and allowing them to reach Brazil and India.

While in Spain he wrote an exceptional treatise on astronomy/astrology in Hebrew, with the title Ha-jibbur Ha-gadol. He published in the printing press of Leiria in 1496, property of Abraão de Ortas the book Biur Luhoth, or in Latin Almanach Perpetuum, which was soon translated into Latin and Spanish. In this book were the astronomical tables (ephemerides) for the years 1497 to 1500, which were instrumental, together with the new astrolabe made of metal and not wood as before, to Vasco da Gama and Pedro Álvares Cabral in their voyages to India and Brazil respectively.

In 1504, while in Tunisia, he wrote a history of the Jewish people, Sefer Hayuhasin, since the Creation of the World until 1500, and several other astronomical/astrological treatises. The History was greatly respected and was reprinted in Cracow in 1581, at Amsterdam in 1717, and at Königsberg in 1857, while a complete edition was published by Filipowski in London in 1857.


Rabbi Abraham Zacuto

(1450-1515; 5210-5275)

The greatest catastrophe of Jewry in exile during the Middle Ages was the series of persecutions and expulsions of the Spanish and Portuguese Jews towards the end of the fifteenth century. One of the great lights of Israel who was destined to Pass through all the stages of this tragic drama, was Rabbi Abraham Zacuto, the famous author of "Sefer Hayuhasin," the first real Jewish chronicle.

Rabbi Abraham Zacuto was born at Salamanca about the middle of the fifteenth century. The stage was then being set for the terrible tragedy which was to destroy the greatest Jewish cultural center in exile. An organized drive by the Catholic Church to exterminate Judaism was beginning to take shape. Salamanca, the seat of much Christian and Jewish learning, was relatively quiet, and the Jews were permitted to carry on their businesses and professions. The family of the Zacutos belonged to the Jewish nobility, and the young Abraham was given every opportunity to acquire a thorough Jewish education under the guidance of the famous Rabbi Isaac Aboab, with whom he later emigrated to Portugal. At the same time the brillant young Jewish nobleman received a secular education which made him an outstanding figure among the young Christian scholars of his day.

Zacuto soon became famous as an excellent mathematician and astronomer. Through the efforts of the Bishop of Salamanca, a great, lover of astronomy, Rabbi Abraham Zacuto was given the chair of astronomy and mathematics at the ancient university of Salamanca. In gratitude Rabbi Abraham Zacuto dedicated to him his first and most famous astronomical work, called "Biur Luhoth," written in excellent and scholarly Hebrew. It was immediately translated into Latin, as "Almanac Perpetuum," and it made an immense impression upon the scholarly world. This work was of great practical value, for it provided a vitally needed tool for discoverers and world travelers who were about to open up the new age of exploration.

Until then anyone setting out on a voyage had to follow the ancient routes along the coasts of the Mediterranean, or other known sea routes. For there was nothing to guide any traveller on the high seas. Rabbi Abraham Zacuto's Almanac was a concise calendar of the constellations of the seven planets. After its publication none of the famous discoverers set out without this Almanac of the Jewish astronomer. With the help of this Almanac they were able to leave the customary routes and venture out into the unknown seas in search of new horizons. Rabbi Abraham Zacuto became famous for this important work. The great astronomers from all over the world corresponded with him and sought his advice and opinion.

After several years of successful reaching at the university of Salamanca, the young rabbi was called to the High University of Saragossa, where an even wider circle of scholars sat at his feet to listen to his lectures on mathematics and astronomy.

When the great tragedy of 1492, the expulsion of the Jews from Spain, was decreed by the cruel Ferdinand and the even more cruel Isabella, Rabbi Abraham Zacuto was promised the highest honors and an abundance of wealth if 'he abandoned his Jewish faith. High dignitaries of the Church offered him their patronage.

Rabbi Abraham Zacuto, however, was a deeply pious Jew. Never before in his brilliant career had he given up an iota of his faith. He had always found much time for the study and teaching of Talmud among his Jewish brethren in Salamanca and Saragossa. He, therefore, spurned all offers of riches and honors for the betrayal of Judaism. 'Willingly Zacuto shared the fate of the hundreds of thousands of unfortunate Jews who had to leave everything behind in search of new shores.

More than a hundred thousand of the Spanish Jews had been granted permission to enter Portugal, at least temporarily, after paying large sums of gold to the greedy king John 11. Not that this monarch was a greater lover of the Jews than his personal enemies, the rulers of Spain. But hopes for much of the wealth of the spanish Jews had induced him to grant a temporary haven to the Jews.

Rabbi Abraham Zacuto was among those who crossed over into Portugal. He settled in Lisbon, where several famous Jewish astronomers and physicians had invited him to assist them at court.

Having barely set foot in Portugal, the impoverished Spanish immigrants were hard hit by epidemics which killed them by the thousand. The cruel King John used this occasion, and the protests of the fanatical population, to rid the country of the bated refugees. lie provided ships for them to cross the seas for new countries. However, these unfortunate people were beset by the most distressing conditions. They had to set out to sea without sufficient food; they were not permitted to land at any harbor, or take on provisions. Thus many perished at sea. Only a small percentage came away with their bare lives and settled in Africa, or some other country.

Rabbi Abraham Zacuto felt a debt of gratitude to Portugal which offered him and many of his brethren a haven of refuge after the cmel expulsion from Spain. He looked forward to years of devoted service to the country of his refuge, and to his own people, which his position at the court would permit him to render.

At that time Vasco de Gains was working on his project of sailing to the fabulously rich India. King John bad already toyed with this proposed expedition. Manuel went about it seriously. Because Rabbi Abraham Zacuto supported it at the court with all his influence and persuasion, Vasco de Gama was finally commissioned to undertake his trip. For this long voyage Vasco de Gama, who bad a Jewish captain by the name of Gaspar, made use of an astrolabe which had been constructed of metal instead of wood, at the suggestion of Rabbi Abrabam Zacuto. With this wise astronomer's tables and astrolabe, the world famous traveller was able to chart his trip across the ocean, guiding himself by the stars.

However, Rabbi Abraham Zacuto was poorly rewarded for his great services to the court and to the land. Face struck another cruel blow at his persecuted brethren, and, although Rabbi Abraham could have escaped it in the shelter of the court, he chose to share it with them.

The turn of events came about when King Manuel of Portugal asked for the hand of the daughter of Ferdinand and Isabella of Spain, who was as cruel as her parents. Through this marriage the two royal houses, so hostile in the past, sought to combine their countries into one mighty Catholic empire.

As a condition. of this marriage, the rulers of Spain demanded that King Manuel follow their example in the persecution of the Jews, and that he join forces with them against the king of France.

The hope of inheriting the crown of Spain was too much of a temptation for the fickle king of Portugal. He deserted his friend, King Charles VII of France, and betrayed his loyal subjects, the Jews.

On the 30th of November, 1496, the marriage contract between the two royal houses was signed. Twenty-four days later King Manuel signed the fatal decree that all Jews and Moors living in his land should either accept the Catholic faith, or leave the country under penalty of death.

In order somewhat to ease his canscience, King Manuel set the date of the expulsion date-line for ten months later, that is, the following October. This would enable those Jews, who were determined to choose expulsion rather than betray their faith, to make preparation to leave the country by ship, since there was no other Way out.

The decree, coming so soon after the expulsion from Spain, was a heartless blow for the helpless Jews. But the ten months' period of "grace" gave them hope that King Manuel might yet change his mind and leave them alone. In the meantime, their leaders, among them Rabbi Abraham Zacuto, tried their best to use their influence with the monarch, but it was in vain. On the contrary, King Manuel was angered by the fact that hardly any Jew took advantage of his "generous" offer which permitted any Jew to save his home and life at the expense of his religion.

King Manuel was further influenced by his personal physician Antonio, an apostate whose Jewish name had been Levi ben Shem-Tov. This traitor bad written a treatise against his former brethren, and tried hard to force the Jews to betray their faith as be had done. He induced the king to take strong measures against the obstinate Jews.

The first step was to close all synagogues and schools. But the Jews continued to pray and study in their private homes, despite the dangers involved.

Then Manuel and Antonio issued a secret order to seize all Jewish children on Easter Sunday, drag them to the churches, and baptize them forcibly.

Rabbi Abraham Zacuto had some good friends among the State Counsellors. One of them told him about the shameful plan of the monarch. immediately, the Jews made plans to hide their children and keep them off the streets.

The king became enraged that his plan failed, and ordered his troops to force their way into the Jewish homes and drag the children out. One of the few Christian Bishops who was opposed to this cruel method, describes the horrible scenes that took place in the streets of Lisbon and other cities. There was such courage among the tortured Jewish parents, that some of them took their own lives and those of their children. The heroism and loyalty to their faith of the Jewish people did not move the heartless king and queen. The soldiers showed great zeal in carrying out their assignment, and went beyond the call of duty. For they seized not small children only, but boys and girls up to the age of twenty. Those who resisted were killed.

The terrorized Jewish population sent a delegation to Pope Alexander VI, with costly presents, to plead with him. to stop the cruel persecution. Pope Alexander asked King Manuel to act in a more humane manner towards the Jews., The situation of the Anussim (Marra-nos) who had been forcibly baptized did ease a little, but that was all.

As the date of the expulsion of the Jews approached, King Manuel increased the pressure upon them with all the means at his disposal. By all kinds of trickery he prevented thousands of Jews from leaving the country. He allowed only Lisbon to be used as a port of departure, and caused various delays, until many, were trapped by the dead-line. According to his decree,. these Jews wen to become his slaves, to do with as he pleased. Of these, thousands upon thousands met cruel death. They refused to buy their freedom at the price of their religion.

Through some miracle, Rabbi Abraham Zacuto and his son Samuel were among the more fortunate ones who saved themselves on board an old ship that was to take them to Africa.

Twice on the way they were caught, by pirates and held for ransom. They were redeemed by kind Jews who paid the ransom After many months of terrible suffering, Rabbi Abraham and his son landed in Tunis. There were not very many who survived the expulsion from Portugal.

There was a flourishing Jewish community in Tunis at that time, under the leadership of the pious and energetic Rabbi Shimon Duran. Rabbi Abraham Zacuto' was . welcomed here with open arms: During the next few years of peace, Rabbi Abraham Zacuto wrote his famous. "Sefer Hayuhasin," a chronological history of the Jews from the Creation of the world to his day. For a long time it was one of the few sources of post-Biblical Jewish history (from the Babylonian exile) to the Middle Ages.

Before this, Rabbi Abraham Zacuto had written a supplement to Rabbi Nathan ben Jehiel's "Sefer Haaruch," a dictionary of the Aramaic language. He is 'also the author of "Arbaim L'Binah," a treatise on astrology.

His stay in North Africa did not last long. The ever increasing threat of a Spanish invasion of Algeria made him take up his wanderer's staff again. Wandering from place to place, Rabbi Abraham Zacuto finally found a haven in Turkey, where Rabbi Joseph Nassi and other influential Jews had provided a new home for many hundreds of the Spanish and Portuguese refugees.

Rabbi Abraham Zacuto died about the year 5275 (1515) without having seen his "Sefer Hayuhasin" published. Fifty years later, however, it was published by Rabbi David Arkish, a physician at the Turkish court, through the generosity of a rich Jewish lady. Thus this most important work of Rabbi Abraham Zacuto found its way into the classical Jewish literature, and won him a place as one of the great men of our people, whose life and work are an everlasting inspiration to us all.

Zacuto’s first book, Ha-Ḥibbur ha-Gadol (The Great Composition), a description of the solar system, was composed between the years 1473 and 1478. Until 1480 he was engaged in scientific astronomical work at the court of the bishop and rector of the University of Salamanca, Gonzalo de Vivero (who remembered him in his will), and in the service of the grand master of the Order of Knights of Alcántara, Juan de Zúñiga y Pimentel. Following the public recognition of Zacuto’s expertise in astronomy, the king of  Portugal, Manuel I (r. 1495–1521), incorporated him into his research staff, which was working on the preparation of astronomical and naval tables.  Christopher Columbus also benefited from Zacuto’s wisdom and used his tables as an important tool in his voyages to the New World. Zacuto’s perfected astrolabe and the astronomical tables he produced were considered the most accurate in existence. He had so great an influence on the voyages of the Portuguese that his contemporary, the historian Gaspar Correia, wrote in his Lendas da Índia that King Manuel said that “he would do nothing without his advice.”

These valuable contributions, however, did not protect Zacuto fro m the edict of expulsionand the mass conversions in Portugal in 1497. On his way out of Portugal he was taken captive twice, but succeeded in reaching a safe haven in Tunis, where he published his celebrated historical outline, Sefer ha-Yuḥasin (Book of Genealogies). In this work of enormous importance in his generation, he recounts the history of the world, particularly the history of the talmudic sages and scholars of Israel up to his own day. The book was first printed in Constantinople in 1566 and again in Cracow in 1580/81.

While in North Africa, in 1498, Zacuto also composed a text in which he applied an astrological theory of history that used eclipses and planetary conjunctions to determine the date of the messianic fulfillment. Zacuto continued his astronomical activity by adapting the tables of the Ḥibbur ha-Gadolfor the year 1501. Later he compiled another set of astronomical tables beginning with the year 1513, arranged for the Jewish calendar and for the meridian of Jerusalem. Zacuto was also the author of a short astrological work entitled Mishpeṭe ha-Ishṭagnin (Judgments of the Astrologer)concerning the years 1518 to 1524. Two of his books on astronomy are known: Be’ur Luḥot, written in Salamanca in 1473 and translated into Latin by José Vicinho as Almanach Perpetuum (Leiria, 1496), and Sefer Tekhunot Zacuto . He also wrote Hosafot le-Sefer ha-ʿArukh (Addenda to Sefer ha-ʿArukh), a rabbinic Aramaic lexicon.

Moises Orfali


Alburquerque, Luis. Almanach Perpetuum de Abraão Zacuto (Lisbon: Imprensa Nacional-Casa da Moeda, 1986).

———. Instruments of Navigation (Lisbon: Comissão Nacional para as Comemorações dos Descobrimentos Portugueses, 1988).

Cantera Burgos, Francisco. Abraham Zacut (Madrid: M. Aguilar, 1935).

Chabás José, and Bernard R. Goldstein. Astronomy in the Iberian Peninsula: Abraham Zacut and the Transition from Manuscript to Print (Philadelphia: American Philosophical Society, 2000).

Levy, Rapahel, “Zacuto’s Astronomical Activity,” Jewish Quarterly Review 26 (1936): 385–386.

Maddison, Francis, “A Consequence of Discovery: Astronomical Navigation in Fifteenth-Century Portugal,” in Studies in the Portuguese Discoveries, ed. Thomas F. Earle and Stephen Parkinson (Warminster, Wilts: Aris & Phillips with the Comissaõ Nacional para as Comemoracões dos Descobrimentos Portugueses, 1992), vol. 1, pp. 71–110.

Shochat, A. “Rabbi Abraham Zacuto in the Talmudical Academy of Rabbi Isaac Shulal in Jerusalem,” Zion 13-14 (1947–48): 43–46 [Hebrew].

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Rabbi Abraham ben Samuel Zacuto's Timeline

August 12, 1452
Salamanca, CL, Spain
Salamanca, Salamanca, Castile and León, Spain
Age 62
Damascus, Dimashq, Syria