阿伯拉罕·伊本·埃兹拉Abraham ibn Ezra

阿伯拉罕·伊本·埃兹拉生活在穆斯林西班牙。关于他的生平所知甚少，只知道他与著名诗人和哲学家Judah ha-Levi关系友好，一些历史学家认为后者是埃兹拉的岳父。Ibn Ezra以学者和诗人闻名。据记载，在他生命的这一时期，直到1140年，他曾前往北非，可能还访问过埃及。

从1140年到1160年，埃兹拉的生活发生了显著变化。在此期间他被迫在欧洲各地漂泊，最终在罗马定居，之后又迁至卢卡，几年后去世。正是在他生命的这后一时期，他创作了他最著名的作品。除了诗歌之外，埃兹拉还撰写了关于[7]的著作：-

……语法、释经、哲学、医学、天文学和占星术。

除了这些主题之外，埃兹拉还撰写了关于排列和组合、历法、星盘以及圣经研究的著作。他尤为重要，因为他在基督教欧洲的学术已被忽视五百年或更久之时，将阿拉伯人的学问传播到了整个欧洲。

在这个致力于数学史的档案中，我们最感兴趣的是埃兹拉关于数的著作。他写了三部关于数的论著，有助于将印度符号和小数思想引起欧洲一些学者的注意。Book of the Unit是一部关于印度符号1、2、3、4、5、6、7、8、9的著作。第二部著作是Book of the Number，描述了整数从左到右按位值的十进制系统。在这部著作中，埃兹拉使用了零，他称之为galgal（意为轮或圆）。尽管有埃兹拉的著作，这些思想在之后的几个世纪里仍未被纳入欧洲数学的主流。

埃兹拉翻译了比鲁尼对花拉子米表格的注释，并对8世纪印度数学传入阿拉伯科学作出了有趣的评论。科学史家今天试图精确量化阿拉伯数学在多大程度上受到印度数学知识的影响，因此埃兹拉关于这一主题的著作被仔细研究。

埃兹拉关于语法和诗歌的著作常常受到“paytanim”的启发[2]：-

会堂开始……任命正式的领祷者，其部分职责是为特别的安息日和节日创作礼拜仪式的诗歌增补。作者被称为“paytanim”（源自希腊语poietes，“诗人”），他们的诗歌被称为“piyyutim”。其主旨是弥赛亚的热情和宗教的狂热。除了使用整个圣经、米示拿和亚兰文词汇外，paytanim还创造了数千个新词。……埃兹拉……攻击早期paytanim的语言和风格；他[是]第一个在宗教诗歌中使用阿拉伯韵律的人。

事实上，对埃兹拉来说，科学与宗教之间没有冲突，因为他认为科学和占星术是犹太学问的基础[7]：-

埃兹拉启示和理性最终是完全一致的。他对圣经文本的批判性阅读以及对某些圣经段落的占星术解释，源于他始终如一地运用自然主义和理性主义的解经方法，并表达了他对理性内在于启示本身这一观点的承诺。

Rabbi Ben Ezra lived in Muslim Spain. Little is known of his life except that he was on friendly terms with the eminent poet and philosopher Judah ha-Levi, whom some historians believe was ibn Ezra's father-in-law. Ibn Ezra made his reputation as a scholar and a poet. It is recorded that during this period of his life, up to 1140, he travelled to North Africa and possibly visited Egypt.

From 1140 to 1160 ibn Ezra's life changed markedly. He was forced to wander throughout Europe during this period and he eventually settled down in Rome, then Lucca, for a few years before his death. It was during this latter period of his life that he composed his most famous works. In addition to his poetry, ibn Ezra wrote on [7]:-

... grammar, exegesis, philosophy, medicine, astronomy, and astrology.

In addition to these topics, ibn Ezra wrote on permutations and combinations, the calendar, the astrolabe, and Biblical studies. He is of particular importance because he spread the learning of the Arabs through Europe at a time when scholarship in Christian Europe had been been neglected for five hundred or more years.

Of the most interest to us in this archive devoted to the history of mathematics is ibn Ezra's work on numbers. He wrote three treatises on numbers which helped to bring the Indian symbols and ideas of decimal fractions to the attention of some of the learned people in Europe. The Book of the Unit is a work on the Indian symbols 1, 2, 3, 4, 5, 6, 7, 8, 9. A second work is the Book of the Number which describes the decimal system for integers with place values from left to right. In this work ibn Ezra uses zero which he calls galgal (meaning wheel or circle). Despite ibn Ezra's books, these ideas would not become accepted into mainstream European mathematics for several more centuries.

Ibn Ezra translated al-Biruni's commentary on al-Khwarizmi's tables and made interesting comments on the introduction of Indian mathematics into Arabic science in the 8th century. Historians of science try today to quantify precisely how much Arabic mathematics was influenced by knowledge of Indian mathematics, so ibn Ezra's writing on this topic are carefully studied.

Ibn Ezra's writings on grammar and poetry were often motivated by the "paytanim" [2]:-

Synagogues began ... to appoint official precentors, part of whose duty it was to compose poetical additions to the liturgy on special Sabbaths and festivals. The authors were called "paytanim" (from the Greek poietes, "poet"), their poems "piyyutim". The keynote was messianic fervour and religious exuberance. Besides employing the entire biblical, Mishnaic, and Aramaic vocabularies, the paytanim coined thousands of new words. ... Abraham ibn Ezra... attacked the language and style of the early paytanim; he [was] the first to use Arabic metres in religious poems.

In fact to ibn Ezra there was no conflict between science and religion for he considered that science and astrology were at the basis of Jewish learning [7]:-

For ibn Ezra revelation and reason are ultimately perfectly congruent. His critical reading of the biblical text and his astrological interpretations of some biblical passages arise from his consistent application of a naturalist and rationalistic exegetical method and express his commitment to the view that rationality is inherent in revelation itself.