  Herz was born to a Jewish scribe and his wife in Berlin in 1747, and received a traditional talmudic education. At the age of fifteen he was sent to apprentice with a Jewish merchant in Königsberg, but at nineteen he matriculated at the university in Königsberg (two years after Herder had left) as a medical student—the only university course open to Jews in Prussia. Medical students were required to study modern languages, philosophy, and mathematics, and Herz became a loyal student of Kant’s, attending his lectures on logic, metaphysics, moral philosophy, natural law, physics, and physical geography. Kant’s selection of the Jewish student for the defense of his inaugural dissertation in 1770 was not accepted happily by some members of the faculty, but Kant supported Herz then and always remained loyal to him, even as the student’s views diverged from his own. Shortly after the defense of Kant’s dissertation, Herz left Königsberg without a degree but with an introduction from Kant to Moses Mendelssohn. He immediately became a member of Mendelssohn’s circle, and also resumed his medical studies in Berlin, and then from 1772 to 1774 in Halle, where he received his doctorate. He then returned to Berlin, where he was appointed to the Jewish hospital. He attended Mendelssohn in his final illness in 1786. Most of Herz’s publications arose from his medical and scientific practice, and included his Letters to Doctors in 1777 and 1784; Outline of All Medical Sciences in 1782, which was adopted as a textbook in Halle; a companion to his Berlin lectures on Experimental Physics; an Essay on Dizziness in 1786; and a controversial essay On Early Burial among the Jews in 1787, in which he argued against the current practice among Jews of burial on the day of death on medical grounds, holding that death could not always be conclusively determined within such a short period. In 1782, Herz also provided the German translation of Manasseh ben Israel’s Vindication of the Jews, to which Mendelssohn provided the preface that would in turn lead the way to his Jerusalem of the next year; Herz thus played a role in the genesis of that central text. In 1777 he began offering private lectures on philosophy in addition to his medical practice, which were well attended. Herz died on January 19, 1803, a year before his teacher Kant.