He obtained a considerable reputation by his lectures on Shakespeare at Leipzig and an explanatory text to Beethoven's music to Egmont. Having refused in 1866 an invitation to take part in the editorship of the Preussische Jahrbücher, in the same year he published his celebrated Zur Kritik und Geschichte des Goetheschen Textes.
He confirmed his reputation by his lectures at the university of Leipzig, and in 1873 accepted the post of extraordinary professor of German literature at Munich specially created for him by Ludwig II of Bavaria. In 1874 he became an ordinary professor, a position which he resigned only in 1889 when he settled at Carlsruhe. He died there on 25 February 1897.
At an early age he became a Jewish Christian, whereas his brother Jakob remained a Rabbinical Jew. Among his other publications were: Briefe Goethes an F. A. Wolf (1868); Zur Entstehungsgeschichte des Schlegelschen Shakespeare (1872); and an introduction to Hirzel's collection entitled Der junge Goethe (1875). He also edited a revised edition of Voss's translation of the Odyssey. From his literary remains were published Schriften zur Kritik und Litteraturgeschichte (1895–1899).
- Zur Kritik und Geschichte des Goetheschen-Textes (1866)
- Briefe Goethes an F. A. Wolf (1868)
- Zur Entstehungsgeschichte des Schlegelschen Shakespeare. Leipzig 1872, new ed. Celtis Verlag, Berlin 2013, ISBN 978-3-944253-02-2
- An introduction to Hirzel’s collection entitled Der junge Goethe (1875)
- A revised edition of Voss’s translation of the Odyssey
- (from his literary remains) Schriften zur Kritik und Litteraturgeschichte (1895–1899)