Abraham bar Ḥiyya

ca. 1065–ca. 1136

Abraham bar Ḥiyya was a philosopher, mathematician, and scientist who lived in Barcelona. He apparently held a position of leadership recognized by both Jewish and non-Jewish communities, but the details are not precisely known. His The Foundations of Understanding and the Tower of Faith (Yesode ha-tevunah u-migdal ha-emunah) was the first Hebrew encyclopedia of science; only the introduction and part of the first treatise are extant. In that and other works, he attempted to render Arabic and Greek scientific terms in Hebrew, thus shaping the evolution of the Hebrew language in the medieval period. Bar Ḥiyya was interested in astrology and once sought to postpone a wedding because the stars were not properly aligned, a position that led to a clash with Judah Barzillai, also of Barcelona. Bar Ḥiyya’s penchant for astrology also manifested itself in detailed eschatological speculations in The Scroll of the Revealer (Megilat ha-megaleh); he deduced that the redemption would arrive in 1383 and that the resurrection of the dead would take place in 1448.

Content by Abraham bar Ḥiyya

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The Book of Intercalation: On the Christian Calendar

Sefer ha-‘ibbur (The Book of Intercalation), Chapter 10
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I have already explained in the previous chapter the method of the nations who calculate according to the moon, namely, the Ishmaelites, as well as the method of those who count exclusively according…

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The Form of the Earth and the Structure of the Heavenly Orbs

Sefer tsurat ha-arets ve-tavnit ha-galgalim (The Form of the Earth and the Structure of the Heavenly Orbs), Introduction
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In the name of the eternal God Let all my speech begin. It is written: O Lord, our Lord, how glorious is Your name in all the earth! Whose majesty is rehearsed above the heavens (Psalms…

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The Foundations of Understanding and the Tower of Faith

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The science that inquires into the creation of existing things and their characteristic forms investigates and examines things that are hidden from the eye and from the bodily senses. One can know…

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Meditation of the Sad Soul

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We will now return to the main topic. The Holy One divided His holy Torah according to the three classes of believers mentioned above. He gave every class its own straight path and statutes, so that…

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Letter to Judah Barzillai of Barcelona

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It is said that the first science of the sciences of the stars is the investigation of the form of the earth and the heavens and their shapes; and to give proofs and evidence that they [the heavens]…

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Scroll of the Revealer

Megilat ha-megaleh (Scroll of the Revealer), Introduction, Chapters 2, 5 (selections)
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Anything whose basic principle is from the Torah and provides good for Israel in this exile, or encourages them in their faith, or serves to increase their trust and hope in God is good for a person…