David ben Yom Tov facts for kids
David ben Yom Tov, also known as David Bonjorn del Barri, was a Catalan Jewish astronomer and astrologer. He lived in the early 1300s. He was likely born in Cotlliure, Catalonia, around 1300. He probably passed away in Barcelona before 1361.
Some experts used to think David ben Yom Tov was the same person as another scholar, David ben Yom Tov ibn Bilia. But now, most scholars believe they were different people.
His Life Story
David ben Yom Tov was born around the year 1300. His other name, Bonjorn, is a Catalan translation of the Hebrew Yom Tov, meaning "good day."
His father, Bonjorn del Barri, was a rich merchant. He lived in Roussillon, which was part of the Catalan Kingdom of Majorca back then. In 1323, the king allowed David's father to join the Jewish community council in Perpignan. He could also travel and trade freely. He didn't have to wear a special badge to show he was Jewish.
By 1327, David's father had passed away. David then asked King James II of Aragon to change some parts of his father's will. For example, the will said David had to move to Perpignan for two years. It also said he couldn't lend money to the new king of Majorca. David successfully got these rules changed. David seemed to be the only son. One of his sisters, Venges, later married a famous Jewish writer, Joseph Caspi.
David ben Yom Tov first married a Jewish woman from Arles. This marriage ended quickly and was not completed. This was because his wife was declared to be unwell.
In 1332, King Alfonso IV of Aragon allowed David to marry again. His new wife was Esther, the daughter of a rich merchant from Girona. Their marriage was difficult. By 1337, Esther wanted a divorce and her dowry back. David refused until Esther took all his books and tools from his study. He complained that his books were so important to him. He said she couldn't have forced him better than by taking them.
David then gave the required divorce paper to the Jewish court in Perpignan. But he tried to cancel parts of the court's decision, probably about the dowry. Legal experts from the king of Majorca tried to help David. But authorities from Esther's hometown, Girona, supported her. A long and loud debate followed. Rabbis from both sides of the Pyrenees mountains shared their opinions. Several records of the case still exist. In the end, the court's first decision was upheld.
Records show David was still living in Perpignan in 1340. He was there again in 1352. At that time, King Peter IV of Aragon sent him a message. The king was asking about some "astrolabe tables" that were late.
A Jewish scholar named Judah Mosconi said he met "David Bonjorn and his father" in Perpignan. This meeting might have been in 1362. Mosconi called David Bonjorn one of the greatest astronomers of his time. Some people think Mosconi might have made a mistake. They believe he meant "David Bonjorn and his son." David Bonjorn's son, Jacob ben David Poel ben Yom Tov, was also a well-known astronomer. Jacob created many astronomical tables in 1361 that were widely copied.
However, this idea is not certain. Jacob also had a son named David. Mosconi might have been talking about him. But if the date 1362 is correct, Jacob's son would have been very young. Another idea is that since Jacob's name was on the tables in 1361, David might have already passed away.
Astrology and Medicine
One of David ben Yom Tov's books that still exists is called Kelal Qatan. This means "Concise summary." It's a short book about how to use astrology in medicine. It mainly focuses on the moon's position. A modern English version is only eleven pages long. Five copies of the book still exist. Four are in Hebrew from the 1400s. One is a Latin translation written in Catalonia before 1446.
David wrote that he created the book for a "distinguished friend." This friend was a "medical expert." The book was meant to be a "concise summary of astrology" that doctors would need every day. It would help them decide when to give certain medicines, like those that make you go to the bathroom or throw up.
He believed a good doctor should know astrology. This would help them understand how the stars affect health. He also thought a good astrologer should know medicine. This would help them prepare people for outside influences. But he also quoted Hippocrates, saying that art is long, but life is short. He meant it's better to be very good at one thing. So, he made a short summary for his friend. He said he took information from other books on the subject. He didn't add much of his own ideas.
David then explained some astrology and astronomy words. He gave rules for good and bad times for medical treatments. These included blood-lettings and medicines. He also gave astrological signs for "critical days" during an illness. He even gave a sign that a patient might do better with a different doctor. But he said these signs are only general. He added that a patient is also affected by their birth chart and, most importantly, by God's will.
David ben Yom Tov said he used other books as his sources. Experts who studied Kelal Qatan found that he used parts of the Centiloquium. This book was thought to be by Ptolemy, whom David mentioned. He also used a commentary on it by Ahmad ibn Yusuf al-Misri. Another source was Sefer ha-Me'orot (1148). This was a book specifically about medical astrology by the famous Jewish scholar Abraham ibn Ezra, whom David also mentioned.
The ideas David ben Yom Tov used were similar to these two sources. However, the way he put the book together was new. Most of his specific rules don't seem to come directly from other known books. But he suggested that many of them were simply results of ideas found in standard astrology tables. He said these tables could be found in astronomical almanacs. A copy of such tables, which David said he would include, is found in the Latin manuscript from Barcelona. These tables are similar to others found with later astronomical tables by Abraham bar Hiyya.
Experts say that astrology was not a main part of Jewish medical practice at that time. But they see David ben Yom Tov's Kelal Qatan as part of a new interest in astrology. This interest grew in Catalonia and Southern France in the 1300s. Other Hebrew works by Shem Tov ben Isaac of Tartosa and Pinchas of Narbonne also show this. So do Latin works by Bartholomew of Bruges, Bernard de Gordon, and Arnau of Villanova.
See also
In Spanish: Jacob ben David Bonjorn para niños
