Rav Dovid Ganz was born in Lippstadt (North Rhine-Westphalia, Germany) in 5301 (1541). He was a great genius who toiled in Torah all his life. He studied in Frankfurt am Main and in Cracow, where he was a talmid muvhak of Rav Moshe Isserles, the Rema, and he was among the disciples of the Maharal of Prague. He eventually settled in Prague where he remained for the rest of his life.
Three of his seforim were published. Tzemach Dovid (1592), on Jewish history, was published by Rav Dovid himself in his lifetime. Magen Dovid on the laws of Kiddush Hachodesh, astronomy, and geography, was published in Prague and over a hundred years after his passing. It had the haskomos of Rav Ephraim Luntschitz, author of the Kli Yakar, Rav Yitzchak Katz, and Rav Yom Tov Lipman Heller, the author of Tosafos Yom Tov. It was later renamed and expanded under the title Nechmad Ve’naim. Rav Dovid also mentions his works, Migdal Dovid and Prozdor, on mathematics, Meor Hakatan, on the calendar, and Gevulos Ha’aretz, but these seforim remained as unpublished handwritten manuscripts.
Some sources add the last name Avazi to Ganz, since Ganz is German for Goose (Avaz, in Hebrew). They base this on the supposition that Gevulos Ha’aretz was published under the pseudonym David Avazi in Constantinople as Tzuras Ha’aretz.
Rav Dovid passed away on the 8th of Elul, 5373 (1613) and was laid to rest in Prague. He left behind two sons, Rav Yisroel of Cracow and Rav Yehoshua Zeligman of Bischitz.
SELECTIONS FROM HIS SEFORIM
The introduction to his sefer, Tzemach Dovid, includes apologetics for his use of non-Jewish historical records and materials and the citation of non-Jewish authors, referring to the early Jewish philosophers who cited Aristotle. He explains that his historical accounts have a great benefit for the Jewish readers since, “The historical accounts and stories in this volume demonstrate Hashem’s Divine Providence—hashgacha pratis over His flock, Am Yisroel. It tells of great, mighty kings who rose to the throne and ruled in various countries, who made it their mission to destroy, uproot, and decimate our people. Yet they failed again and again because Hashem saved us from them and fulfilled His promise to protect us.” He concludes, “The readers can read of monarchs who ruled their nations, while we in our exile have no king. This should motivate our prayers to ‘return our judges’ and righteous monarchy to us as in the days of old and cause us to ‘yearn for the flourishing of Tzemach Dovid – the offspring of Dovid [the Mashiach]’, amen, may it be His will.” (Tzemach Dovid, Introduction.) He explains that this is why he named the sefer and why he wrote it.
This sefer, Tzemach Dovid, was translated into Latin by Wilhelm Heinrich Vorst (Leiden, 1644) and later into Yiddish by Solomon (Shlomo Zalman) Hanau (Frankfurt, 1692).
Rav Dovid Ganz worked with the famous astronomers, Tycho Brahe and Johannes Kepler, and was one of the first to cite Copernicus’s heliocentric theory in Hebrew, through his seforim.
In his sefer, Nechmad Ve’naim (No. 8), he cites Euclid’s ‘Elements’ (a thirteen-part work, which he read in translation by Moshe ibn Tibon, and is considered the foundation of modern geometry, mathematics, algebra, logic, and number theory). He describes it as the foundation of all the wisdom of the gentile nations, and considers Euclid the most brilliant and wise of the non-Jewish savants. He compared the work to a ladder reaching the heavens, because without such a ladder there is no way to ascend.
He also writes in Nechmad Venaim (Ch. 2, No. 4) of his three visits to Tycho Brahe’s astronomical observatory in Prague, where for five days at a time they observed, recorded, and charted the heavenly bodies. He describes there his use of telescopes for stargazing.
In the same sefer (Shaar 1, siman 25), Rav Ganz relates how Kepler and Brahe described the geocentric and heliocentric models of the universe to him and he, in turn, taught them that the Gemara (Maseches Pesachim 94b) describes the machlokes between the gentile scholars and our sages regarding this debate. According to Rav Ganz, Brahe replied, “It was incorrect of your sages to have conceded to the gentile scholars regarding this, for the sages of Israel were correct in their own opinion.”
Rav Ganz was a historian, mathematician, cartographer, and astronomer. He is remembered as one of the first Ashkenazi Jews to delve deeply into the bastions of secular knowledge and wisdom of his day and still remain faithful, heart and soul, to his people and Hashem’s Torah.
