"The best man of his time, unique in his knowledge of all the ancient sciences. He is called the Philosopher of the Arabs. His books deal with different sciences, such as logic, philosophy, geometry, arithmetic, astronomy etc. We have connected him with the natural philosophers because of his prominence in Science." – as described by the historian Ibn al-Nadim

          "bu Yusef Yaqoub ibn Ishaq Al-Kindi says :We ought not to be embarrassed of appreciating the truth and of obtaining it wherever it comes from, even if it comes from races distant and nations different from us. Nothing should be dearer to the seeker of truth than the truth itself, and there is no deterioration of the truth, nor belittling either of one who speaks it or conveys it." -

Al-Kindi is known in the West as Alkindus

He was popularly known as the 'Philosopher of the Arabs' in the Middle Ages. Cardano considered Al-Kindi as one of the twelve greatest minds of the Middle Ages. He is among a small group of Muslim scientists who made original contributions in many fields. Al-Kindi was a philosopher, astronomer, physician, mathematician, physicist, and geographer. He also was an expert in music.

 Yaqub Ibn Ishaq al-Kindi was born at Kufa (present Iraq) in 800 C.E. His father worked for Khalifah (Caliph) Haroon al-Rashid. Al-Kindi spent his long career in Baghdad and was a contemporary of al-Mutawakkil, al-Mamun and al-Mu'tasim. He died in 873 C.E. during the reign of al-M'utamid.

  Al-Kindi was the first physician who systematically determined the dosage for most drugs.

It greatly helped in the development of dosage standards (prescription) for patients. There are more than thirty treatises attributed to al-Kindi in the field of medicine, in which he was chiefly influenced by the ideas of Galen. His most important work in this field is probably De Gradibus, in which he demonstrates the application of mathematics to medicine, particularly in the field of pharmacology. For example, he developed a mathematical scale to quantify the strength of drug and a system, based the phases of the moon, that would allow a doctor to determine in advance the most critical days of a patient's illness.

   Al-Kindi was a pioneer in cryptanalysis and cryptology.

He is credited with developing a method whereby variations in the frequency of the occurrence of letters could be analyzed and exploited to break ciphers (i.e. crypanalysis by frequency analysis). This was detailed in a text recently rediscovered in the Ottoman archives in Istanbul, A Manuscript on Deciphering Cryptographic Messages, which also covers methods of cryptanalysis, encipherments, cryptanalysis of certain encipherments, and statistical analysis of letters and letter combinations in Arabic.This is the first page of al-Kindi's manuscript "On Deciphering Cryptographic Messages", containing the oldest known description of cryptanalysis by frequency analysis

 In the field of Chemistry

Al-Kindi argued that base metals cannot be converted to precious metals. In contrast to prevailing alchemical views, he was emphatic that chemical reactions cannot bring about the transformation of elements.

 Al-Kindi's original work provided the foundation for modern arithmetic

 He made original contributions to geometrical optics, a special field of Physics, and wrote a book on it. He also wrote four books in mathematics, on the number system. No doubt the Arabic system of numerals was largely developed by al_Khawarizmi but al-Kindi also made rich contributions to it. He also contributed to spherical geometry to help him in astronomical studies. Several centuries later, Al-Kindi's work inspired Roger Bacon.

 Al-Kindi researched on the scientific aspects of music

 He stated that the various notes that combine to produce harmony have a specific pitch, and the degree of harmony depends on the frequency of notes. Further, he provided a method for the determination of pitch. Al-Kindi stated that when a sound is produced it generates waves in the air, which strike the eardrum.

 Al-Kindi wrote more than two hundred forty books

Among them are 16 books in Astronomy, 22 each in Medicine and Philosophy, 12 in Physics, 32 in Geometry, 11 in Arithmetic, 9 in Logic, 4 on the number system, 7 in Music and 5 in Psychology. In addition, he wrote monographs on astronomical instruments, tides, rocks and precious stones. Gerard of Cremona translated many of his books into Latin. These books include Ikhtiyarat al-Ayyam, al-Mosiqa, Risalah dar Tanjim, Ilahyat-e-Aristu, Mad-o-Jazr and Adviyah Murakkaba.

Al-Kindi's influence on the development of physics, mathematics, medicine, philosophy and music lasted for several centuries. It is amazing how he was able to make original contributions to all of these fields.