Of the renowned Arnstein Family of dominant court financiers in Vienna in the 18th and first half of 19th century. The Arnsteins married into other leading Jewish families, such as Gomperz, Itzig, Mendelssohn and Pereira.
Son of Isaac Aaron, married Sibylle (Bella) Gomperz (daughter of Bendit Gomperz -Nymwegen). Became Head of the Arnstein Firm and food supplier to Empress Maria Theresa’s husband . His ties with the Court brought him privileges and he was freed from humiliating restrictions (1762-1768).
He was active in matters affecting the Jewish community in Austria , such as preventing the expulsion of Jews from Prague (1744-45), and assisting the Jews of Hamburg concerning their rights.