Abu'l-Barakāt Hibat Allah ibn Malkā al-Baghdādī (; c. 1080 – 1164 or 1165 CE) was an Islamic philosopher, physician and physicist of Jewish descent from Baghdad, Iraq. Abu'l-Barakāt, an older contemporary of Maimonides, was originally known by his Hebrew birth name Baruch ben Malka and was given the name of Nathanel by his pupil Isaac ben Ezra before his conversion from Judaism to Islam later in his life. His writings include the anti-Aristotelian philosophical work Kitāb al-Muʿtabar ("The Book of What Has Been Established by Personal Reflection"); a philosophical commentary on the Kohelet; and the treatise "On the Reason Why the Stars Are Visible at Night and Hidden in Daytime". Abu'l-Barakāt was an Aristotelian philosopher who in many respects followed Ibn Sina, but also developed his own ideas. He proposed an explanation of the acceleration of falling bodies by the accumulation of successive increments of power with successive increments of velocity. His thought influenced the Illuminationist school of classical Islamic philosophy, the medieval Jewish philosopher Ibn Kammuna, and the medieval Christian philosophers Jean Buridan and Albert of Saxony. Life Abu'l-Barakāt, famed as Awḥad al-Zamān (Unique One of his Time), was born in Balad, a town on the Tigris above Mosul in modern-day Iraq. As a renowned physician, he served at the courts of the caliphs of Baghdad and the Seljuk sultans. He converted to Islam later in his life. Abu'l Barakat does not refer to his conversion in his writings, and the historical sources give contradictory episodes of his conversion. According to the various reports, he converted either out of "wounded pride", fear of the personal consequences of the death of Sultan Mahmud's wife while under his care as a physician or fear of execution when he was taken prisoner in a battle between the armies of the caliph and that of the sultan. Ayala Eliyahu argues that the conversion was "probably motivated by convenience reasons". Isaac, the son of the Abraham Ibn Ezra and the son-in-law of Judah Halevi, was one of his pupils, to whom Abu'l-Barakāt, Jewish at the time, dictated a long philosophical commentary on Ecclesiastes, written in Arabic using the Hebrew alphabet. Isaac wrote a poem in his honour as introduction to this work. Philosophy Experimental method Al-Baghdadi described an early scientific method emphasizing repeated experimentation, influenced by Ibn Sina, as follows: Motion Al-Baghdadi was a follower of the scientific and philosophical teachings of Ibn Sina.