Abu Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī, known as the Philosopher of the Arabs, was a Muslim Arab philosopher, polymath, mathematician, physician and musician. Al-Kindi was a descendant of the Kinda tribe and he was born in Basra and educated in Baghdad. In the field of mathematics, al-Kindi played an important role in introducing Indian numerals to the Islamic and he was a pioneer in cryptanalysis and devised several new methods of breaking ciphers. Using his mathematical and medical expertise, he was able to develop a scale that would allow doctors to quantify the potency of their medication, the central theme underpinning al-Kindis philosophical writings is the compatibility between philosophy and other orthodox Islamic sciences, particularly theology. And many of his works deal with subjects that theology had an immediate interest in and these include the nature of God, the soul and prophetic knowledge. Al-Kindi was born in Kufa to a family of the Kinda tribe, descended from the chieftain al-Ashath ibn Qays. His father Ishaq was the governor of Kufa, and al-Kindi received his education there. He later went to complete his studies in Baghdad, where he was patronized by the Abbasid caliphs al-Mamun and he was also well known for his beautiful calligraphy, and at one point was employed as a calligrapher by al-Mutawakkil. When al-Mamun died, his brother, al-Mutasim became Caliph, al-Kindis position would be enhanced under al-Mutasim, who appointed him as a tutor to his son. But on the accession of al-Wathiq, and especially of al-Mutawakkil, henry Corbin, an authority on Islamic studies, says that in 873, al-Kindi died a lonely man, in Baghdad during the reign of al-Mutamid. After his death, al-Kindis philosophical works quickly fell into obscurity and many of them were lost even to later Islamic scholars, felix Klein-Franke suggests a number of reasons for this, aside from the militant orthodoxy of al-Mutawakkil, the Mongols also destroyed countless libraries during their invasion. Al-Kindi was a master of different areas of thought and was held to be one of the greatest Islamic philosophers of his time. The Italian Renaissance scholar Geralomo Cardano considered him one of the twelve greatest minds of the Middle Ages, according to Ibn al-Nadim, al-Kindi wrote at least two hundred and sixty books, contributing heavily to geometry, medicine and philosophy, logic, and physics. His influence in the fields of physics, mathematics, medicine, philosophy and music were far-reaching and his greatest contribution to the development of Islamic philosophy was his efforts to make Greek thought both accessible and acceptable to a Muslim audience. Al-Kindi carried out this mission from the House of Wisdom, an institute of translation and learning patronized by the Abbasid Caliphs, in Baghdad. In his writings, one of al-Kindis central concerns was to demonstrate the compatibility between philosophy and natural theology on the one hand, and revealed or speculative theology on the other. Despite this, he did make clear that he believed revelation was a source of knowledge to reason because it guaranteed matters of faith that reason could not uncover. This was an important factor in the introduction and popularization of Greek philosophy in the Muslim intellectual world
Portrait of al-Kindi
Ancient Greek philosophers such as Plato and Aristotle were highly respected in the medieval Islamic world.
The first page of al-Kindi's manuscript "On Deciphering Cryptographic Messages", containing the oldest known description of cryptanalysis by frequency analysis.