Question: Who said that the most influential figure in Islamic philosophy was one of the greatest thinkers?

Knowledge 1: History of science
Ibn Sina (Avicenna) is regarded as the most influential philosopher of Islam. He pioneered the science of experimental medicine and was the first physician to conduct clinical trials. His two most notable works in medicine are the Kitāb al-shifāʾ ("Book of Healing") and The Canon of Medicine, both of which were used as standard medicinal texts in both the Muslim world and in Europe well into the 17th century. Amongst his many contributions are the discovery of the contagious nature of infectious diseases, and the introduction of clinical pharmacology. [SEP] Knowledge 2: Avicenna
George Sarton, the author of The History of Science, described Ibn Sīnā as "one of the greatest thinkers and medical scholars in history" and called him "the most famous scientist of Islam and one of the most famous of all races, places, and times." He was one of the Islamic world's leading writers in the field of medicine. Along with Rhazes, Abulcasis, Ibn al-Nafis, and al-Ibadi, Ibn Sīnā is considered an important compiler of early Muslim medicine. He is remembered in the Western history of medicine as a major historical figure who made important contributions to medicine and the European Renaissance. His medical texts were unusual in that where controversy existed between Galen and Aristotle's views on medical matters (such as anatomy), he preferred to side with Aristotle, where necessary updating Aristotle's position to take into account post-Aristotelian advances in anatomical knowledge. Aristotle's dominant intellectual influence among medieval European scholars meant that Avicenna's linking of Galen's medical writings with Aristotle's philosophical writings in the Canon of Medicine (along with its comprehensive and logical organisation of knowledge) significantly increased Avicenna's importance in medieval Europe in comparison to other Islamic writers on medicine. His influence following translation of the Canon was such that from the early fourteenth to the mid-sixteenth centuries he was ranked with Hippocrates and Galen as one of the acknowledged authorities, princeps medicorum ("prince of physicians").
Knowledge 1: Muslim world
One of the common definitions for "Islamic philosophy" is "the style of philosophy produced within the framework of Islamic culture." Islamic philosophy, in this definition is neither necessarily concerned with religious issues, nor is exclusively produced by Muslims. The Persian scholar Ibn Sina (Avicenna) (980–1037) had more than 450 books attributed to him. His writings were concerned with various subjects, most notably philosophy and medicine. His medical textbook The Canon of Medicine was used as the standard text in European universities for centuries. He also wrote The Book of Healing, an influential scientific and philosophical encyclopedia. [SEP] Knowledge 2: Avicenna
George Sarton, the author of The History of Science, described Ibn Sīnā as "one of the greatest thinkers and medical scholars in history" and called him "the most famous scientist of Islam and one of the most famous of all races, places, and times." He was one of the Islamic world's leading writers in the field of medicine. Along with Rhazes, Abulcasis, Ibn al-Nafis, and al-Ibadi, Ibn Sīnā is considered an important compiler of early Muslim medicine. He is remembered in the Western history of medicine as a major historical figure who made important contributions to medicine and the European Renaissance. His medical texts were unusual in that where controversy existed between Galen and Aristotle's views on medical matters (such as anatomy), he preferred to side with Aristotle, where necessary updating Aristotle's position to take into account post-Aristotelian advances in anatomical knowledge. Aristotle's dominant intellectual influence among medieval European scholars meant that Avicenna's linking of Galen's medical writings with Aristotle's philosophical writings in the Canon of Medicine (along with its comprehensive and logical organisation of knowledge) significantly increased Avicenna's importance in medieval Europe in comparison to other Islamic writers on medicine. His influence following translation of the Canon was such that from the early fourteenth to the mid-sixteenth centuries he was ranked with Hippocrates and Galen as one of the acknowledged authorities, princeps medicorum ("prince of physicians").
Knowledge 1: Avicenna
Early Islamic philosophy and Islamic metaphysics, imbued as it is with Islamic theology, distinguishes more clearly than Aristotelianism between essence and existence. Whereas existence is the domain of the contingent and the accidental, essence endures within a being beyond the accidental. The philosophy of Ibn Sīnā, particularly that part relating to metaphysics, owes much to al-Farabi. The search for a definitive Islamic philosophy separate from Occasionalism can be seen in what is left of his work. [SEP] Knowledge 2: Avicenna
George Sarton, the author of The History of Science, described Ibn Sīnā as "one of the greatest thinkers and medical scholars in history" and called him "the most famous scientist of Islam and one of the most famous of all races, places, and times." He was one of the Islamic world's leading writers in the field of medicine. Along with Rhazes, Abulcasis, Ibn al-Nafis, and al-Ibadi, Ibn Sīnā is considered an important compiler of early Muslim medicine. He is remembered in the Western history of medicine as a major historical figure who made important contributions to medicine and the European Renaissance. His medical texts were unusual in that where controversy existed between Galen and Aristotle's views on medical matters (such as anatomy), he preferred to side with Aristotle, where necessary updating Aristotle's position to take into account post-Aristotelian advances in anatomical knowledge. Aristotle's dominant intellectual influence among medieval European scholars meant that Avicenna's linking of Galen's medical writings with Aristotle's philosophical writings in the Canon of Medicine (along with its comprehensive and logical organisation of knowledge) significantly increased Avicenna's importance in medieval Europe in comparison to other Islamic writers on medicine. His influence following translation of the Canon was such that from the early fourteenth to the mid-sixteenth centuries he was ranked with Hippocrates and Galen as one of the acknowledged authorities, princeps medicorum ("prince of physicians").

Answer: George Sarton