Alexander Zemlinsky or Alexander von Zemlinsky was an Austrian composer, conductor, and teacher. Zemlinsky was born in Vienna to a highly multicultural family. Alexander studied the piano from a young age. He played the organ in his synagogue on holidays, and was admitted to the Vienna Conservatory in 1884. Zemlinsky also met Arnold Schoenberg when the latter joined Polyhymnia, an orchestra in which he played cello and helped found in 1895. The two became close friends and later mutual admirers and brothers-in-law when Schoenberg married his sister Mathilde. Zemlinsky gave Schoenberg lessons in counterpoint, thus becoming the only formal music teacher Schoenberg would have. In 1897 Zemlinsky's Symphony No. 2 (chronologically the third he had written, and sometimes numbered as such) was a success when premiered in Vienna. His reputation as a composer was further helped when Gustav Mahler conducted the premiere of his opera Es war einmal (Once Upon a Time) at the Hofoper in 1900. In 1899 Zemlinsky secured the post of Kapellmeister at Vienna's Carltheater.