astronomy

Jacob ben David ben Yom Tov

Jacob ben David ben Yom Tov is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jacob ben David ben Yom Tov rather than just read about it. In short: Jacob ben David ben Yom Tov (also Yomtob or Jomtob or Bonjourn or Bonet), also known as ha-Poel (or Fu'al), was a Catalan Jewish astronomer and astrologer. He lived, probably at Perpignan, in southern France in the fourteenth century.

Key takeaways

Jacob ben David ben Yom Tov belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jacob ben David ben Yom Tov to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jacob ben David ben Yom Tov from memory before moving on to harder problems.

Reference excerpt

Jacob ben David ben Yom Tov (also Yomtob or Jomtob or Bonjourn or Bonet), also known as ha-Poel (or Fu'al), was a Catalan Jewish astronomer and astrologer. He lived, probably at Perpignan, in southern France in the fourteenth century. He was the author of astronomical tables prepared at Perpignan in 1361. These tables, still extant in manuscript (Bibliothèque Nationale, Paris, MS. No. 10,901; Adolf Neubauer, "Cat. Bodl. Hebr. MSS." No. 2072, 2), enjoyed a great reputation. They were translated into Latin in the fifteenth century, and were the subject of many Hebrew commentaries, among which was one written by Joseph ben Saul Ḳimḥi (MS Casanatense 3155). Many manuscripts of these tables were retranslated from Latin into Hebrew. His father David ben Yom-Tov, also called David Bongoron, was identified in the past with the Portuguese Jewish philosopher David ben Yom-Tov ibn Bilia by some scholars, including the nineteenth century scholar Moritz Steinschneider. However the two are now believed to have been separate individuals.

References José Chabás (December 1991), "The astronomical tables of Jacob ben David Bonjorn", Archive for History of Exact Sciences, 42 (4), 279–314. doi:10.1007/BF00375156 Josep Chabas i Bergon, Antoni Roca i Rossell, and Xavier Rodriguez i Gil (1992), L'astronomia de Jacob ben David Bonjorn. (in Catalan). Barcelona: Institut d'estudis catalans. ISBN 84-7283-216-3. Google books (Review) Gerrit Bos, Charles Burnett, and Tzvi Langermann (2005), "Hebrew Medical Astrology: David Ben Yom Tov, Kelal Qaṭan: Original Hebrew Text, Medieval Latin Translation, Modern English Translation", Transactions of the American Philosophical Society (New Series) 95 (5), pp. i, iii, v-vii, ix, 1-61, 63-121

Jewish Encyclopedia Bibliography Moritz Steinschneider (1893), Die Hebräischen Übersetzungen des Mittelalters und die-Juden als Dolmetscher, etc... (Berlin) p. 615; Berliner's Magazin, xvi. 49; Ernest Renan-Adolf Neubauer, Les Ecrivains Juifs Français, p. 355.

Notes

External links Manuscript This article incorporates text from a publication now in the public domain: Gottheil, Richard; Broydé, Isaac (1902). "Bonet, Jacob ben David ben Yom-Ṭob (Bonjorn)". In Singer, Isidore; et al. (eds.). The Jewish Encyclopedia. Vol. 3. New York: Funk & Wagnalls. p. 305.

Worked examples

Example 1 — a first encounter with Jacob ben David ben Yom Tov

Start with the simplest possible case. Write down what Jacob ben David ben Yom Tov claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jacob ben David ben Yom Tov before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jacob ben David ben Yom Tov ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jacob ben David ben Yom Tov

In research: Jacob ben David ben Yom Tov appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jacob ben David ben Yom Tov in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jacob ben David ben Yom Tov is common in secondary-school and first-year university syllabi. It links to neighbouring topics 14th-century Catalan Jews, 14th-century Catalan people, 14th-century astrologers, so understanding it makes those chapters shorter.
In everyday life: Look for Jacob ben David ben Yom Tov outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jacob ben David ben Yom Tov in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jacob ben David ben Yom Tov means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jacob ben David ben Yom Tov out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jacob ben David ben Yom Tov in simple terms?

Why does Jacob ben David ben Yom Tov matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jacob ben David ben Yom Tov?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jacob ben David ben Yom Tov.