Al-Kindi is the nickname of Abu Yusuf Ya’qub ibn Ishak al-Kindi. The 9th century was the golden age of the development of Islamic science, when the Arabs became the true standard holders of civilization. They not only saved Greek teachings from extinction, but also made lasting contributions to almost all branches of science, and provided an impetus for humanitarian activities. The leading scientists in the early 9th century were al-Kindi, al-Khwarizmi, and al-Farghani. Al-Kindi is a genius and versatile. He can be considered as one of the greatest translators of Muslims.
Al-Kindi from the tribe of Kinda in South Arabia. He was born in Basra in the early 19th century. In the West it is known as Al-Kindus. His father, Ishak ibn Salih was governor of the Kufa during the reign of the Abbasid Caliphs, Mahdi, Hadi, and Harun ar-Rashid.
Al-Kindi in youth studying in Basra and Baghdad. He was very dear to the Caliph Ma’mun ar-Rashid and was given various positions in the state. Despite this, he also often experienced pressure from orthodox groups during the leadership of al-Mutawakkil (847-861 AD). He studied science in the fields of medicine, philosophy, mathematics, magic, music, and logic. He mastered Persian, Greek, and Indian teachings, and was fluent in Hebrew, Greek, and Arabic. Due to this ability, he was appointed to translate Greek works during the reign of Ma’mun.
One of the sons of Caliph Mu’tasim became his student and later seconded as an astrologer at the Abbasid Palace. However, he was captured by Mutawakkil and his library was confiscated.
Al-Kindi is an encyclopedic scientist and has contributed to the fields of mathematics, astrology, astronomy, physics, optics, music, medicine, pharmacy, philosophy, and logic. No fewer than 265 works were stated as his essays. However, only a few are still in the original language.
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Of al-Kindi’s 265 works, 22 special works discuss philosophy, 19 on astronomy, 16 on astrology, 7 on music, 11 on mathematics, 22 on numbers, 22 on medicine, 21 on politics, 33 about physics, 9 about logic, and the rest is about other branches of science. Al-Kindi also made and revised a number of translations of Greek works into Arabic.
Among the important works of al-Kindi for example:
- De Aspectibus, a text on geometrical and physiological optics, which influenced the thinking of Roger Bacon, Wirelo, and a number of other Western scientists.
- De Medicinarum Compesitarum Gradibus, an extraordinary manuscript that deals with physiological geometry and optics. It departed from Euclid’s optics at Theons and was widely used in the West and in the east until it was replaced by the larger works of Ibn al-Haitham. In this work, al-Kindi discusses the trajectory of light in straight lines of the direct process of vision, the process of seeing using glass, and the effect of distance and angle of vision or seeing with glass tricks. He also said that light travel does not take time.
One of his works, translated into Latin, explains the causes of the blue color in the sky. He said: “The color actually does not come from the sky just like that, but comes from a mixture of the darkness of the sky with the light atoms of dust, vapor, etc., which are illuminated in the air by the sun’s light.”
He also translated and commented on a number of Aristotle’s philosophical works. His theory of the universe went hand in hand with Aristotle’s theory. According to al-Kindi, the world as a whole is the work of an external activity, namely divine intelligence whose activities are transmitted in various ways from above to the surface of the earth. Between God and the world, or the human body, lies a spirit capable of creating a heavenly situation. As long as the spirit is in harmony with the body, it is dependent on good influences, but in it there is a spiritual source that makes man free. Both, namely freedom and immortality exist only in the world of intelligence. If a person can have both, his intellectual power is so extensive that he is capable of obtaining true knowledge of God and the universe. So in his book De Intelectu, which was translated into Latin, and edited by Nagy, the Western world discovered for the first time the teachings of intelligence.