Art critic; museum director (1947-1963); professor of art history (1952-1968); Van Gogh expert. Hammacher grew up in Middelburg as a sensitive child with strong affinities for music, literature, and painting. He played the violin, painted and drew. In 1917, after graduating from high school, he went to Utrecht to study law, with a view to becoming an attorney, like his uncle and grandfather. One year later, however, he changed his mind and started writing on literature and art.