Background
He was born into an old, established Rhenish merchant family.
He was born into an old, established Rhenish merchant family.
From 1863 to 1868, he studied with Oswald Achenbach at the Kunstakademie Düsseldorf.
In 1871, he was summoned to the Weimar Saxon-Grand Ducal Art School to teach landscape painting as a replacement for Max Schmidt, who had left to take another position. Three years later, he received a permanent appointment. He was head of the art department from 1876 to 1881, but grew tired of his administrative duties and returned to teaching.
His best-known students were Christian Rohlfs, Hanns Diehl, and Franz Bunke.
He was one of the founders of German Impressionism. After trying out several styles during his early years, he became attracted to the plein-air painting of the French Barbizon School.
A street in Weimar has been named the Theodor-Hagen-Weg in his honor and his home (now Trierer Straße 36) is a municipal monument.
From 1893, he was a member of the Munich Secession and, from 1902, the Berlin Secession.