philologist who pioneered in the collection and study of Norwegian folk songs, gathered a massive quantity of ancient Norwegian inscriptions, and prepared what is considered to be one of the most outstanding critical editions of the Poetic Edda, the 13th-century Icelandic collection of heroic and mythological poetry. His edition of Old Norse folk songs appeared in 1858.

Professor of comparative philology and Old Norse at the University of Christiania (Oslo) from 1866, he published Norraen fornkvaedi, his edition of the Edda, in 1867. He maintained that the songs of the Edda and the earlier sagas were largely founded on Christian and Latin tradition imported to Scandinavia by way of England. Publication of his monumental edition of inscriptions began in 1891. His writings also include Helgedigtene i den aeldre Edda (1896; The Home of the Eddic Poems).