Johannes Classen

He studied philology at the University of Leipzig, afterwards continuing his education at Bonn, where he was a student of Barthold Georg Niebuhr.

From 1827 he lived in the home of Niebuhr, whose son Marcus was tutored by Classen.

After the death of Niebuhr on January 2, 1831, and of his wife nine days later, Classen took care of his former teacher's three children.

In 1829 he received his habilitation at Bonn, and in 1832 served as an assistant at the Joachimsthalsche Gymnasium in Berlin.

Classen's most extensive literary effort was an eight-volume publication on the works of Thucydides (Thukydides, 1862–1889).