The first major Arab philosopher, who worked alongside the Mutazilah in Baghdad but also sought from Greek sages. Al-Kindi worked closely with the Mutazilites - al-Farabi, Ibn Sina and Ibn Rushd, the great Muslim philosophers, who were all affected by the missionary zeal of the Muttazilite movement which laid great emphasis on Ma'akulat (reason) than on Mankulat (tradition) - in their attempt to rid theology (kalam) of anthropomorphism, but he did not confine himself, as they did, to Muslim sources, but sought wisdom also from the Greek sages. Al-Kindi was the first Arab philosopher to develop the philosophical conception of Greek thought. Al-Kindi applied Aristotle's proof for the existence of the First Cause to the God of the Qura'an. Like all the later philosophers, he believed that Muslims should seek truth wherever it was found, even from foreign people whose religion was different from their own. Al-Kindi acquainted with philosophy of India and Greece because Baghdad at the time was the seat of learning and many books from Greek and Sanskrit had already been translated into Arabic. Al-Kindi's work affected the intellectual development of Western Europe in the 13th and 14th centuries. On The Intellect and The Theory of the magical arts' were his two most important works. He was the tutor to the son of al-Mustasim the Caliph of Baghdad. Al-Kindi contributed to spherical geometry to assist him in astronomical studies. In chemistry he opposed the idea that base metals can be converted to precious metals. In physics, he made rich contributions to geometrical optics and wrote a book on it. This book later on provided guidance and inspiration to such eminent scientist as Roger Bacon. In medicine, al-Kindi's chief contribution comprises the fact that he was the first to systematically determine the doses to be administered of all the drugs known at his time. This resolved the conflicting views prevailing among physicians on the dosage that caused difficulties in writing prescriptions. In music, al-Kindi pointed out that the various notes that combine to produce harmony; each note has a specific pitch. Thus, notes with low or too high a pitch is non-pleasant. The degree of harmony depends on the frequency of notes, etc. He also pointed out the fact that when sound is produced, it generates waves in the air, which strike the eardrum. Al-Kindi was known as Alkindus in Latin and a large number of his books were translated into Latin by Gherard of Cremona. His influence on development of science and philosophy was significant in the revival of science in that period hence in the Middle Ages, Cardano considered him as one of the twelve greatest minds. Al-Kindi was a prolific writer; the total number of books written by him was 241 in Astronomy, Arithmetic, Geometry, Medicine, Physics, Philosophy, Logic, Psychology and Music. Al-Kindi whose full name was Abu Yousuf Yaqub Ibn Ishaq al-Kindi was born in Kufa and educated in Basra, he settled finally in Baghdad, (His father was an official of Haroon al-Rashid) where he enjoyed the patronage of al-Mamun.