Al-Khalil's was born in Oman and grew up in Basra, Iraq (718-786 A.D). He was fond of study and research; he was one of the earliest Arab lexicographer and Linguists. He stayed constantly and adhered to his scholars and teachers until he became the first teacher in Basra in Arabic language, grammar, music and Arabic prosody.
His best known contributions are Kitab al-'Ayn regarded as the first dictionary (lexicon) of the Arabic Language, the current standard for Harakat (vowel marks in Arabic script), and the invention al-'arud (the study of Arabic prosody)[1]. Al-Ayn is an Arabic lexicon in which, we can say, Al-Khalil has mentioned and collect all the words' roots of Arabic Language by following a changing method of the letters that a word consists of. "The dictionary was not arranged alphabetically but rather by phonetics, following the pattern of pronunciation of the Arabic alphabet from the deepest letter of the throat ﻉ (ayn) to the last letter pronounced by the lips, that being م (miem)"[2].
Invention of Arabic Prosody (Al-Arud):
The idea of creating prosody came up to Al-Khalil's mind when he was walking in the market of coppersmiths, the voice of the distinctive beat tunes brought back to his mind the prosody of Arabic poetry. He went back home and went down into the well and began to produce sounds with different tones to identify the appropriate meter for each poem. He devoted himself to study Arabs poems' rhythms and meters which he found that all Arabic poems consist of 16 meters.
In spite of this profuse science and innovative mentality, Al-Khalil was ascetic and pious. He lived in a cottage in Al-Basra, possessed nothing, while his students earned money by his knowledge.
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[1] Wikipedia Website.
[2] Wikipedia