Johan Ernst Welhaven Sars was a Norwegian professor, historian, author and editor. Assuming perspectives from the positivism philosophical school, his main work was Udsigt over den norske Historie, four volumes issued from 1873 to 1891. He co-edited the magazines Nyt norsk Tidskrift from 1877 to 1878, and Nyt Tidsskrift from 1882 to 1887. He was politically active for the Liberal Party of Norway and among the party's most central theoreticians.

Nyt Tidsskrift is a former Norwegian literary, cultural and political periodical issued from 1882 to 1887, and with a second series from 1892 to 1895. The periodical had contributions from several of the leading intellectuals of the time, including later Nobel Literature Prize laureate Bjørnstjerne Bjørnson, later Nobel Peace Prize laureate Fredrik Bajer, the writers Alexander L. Kielland, Jonas Lie, Arne Garborg and Hans Aanrud, proponents for women's rights Camilla Collett, Gina Krog and Hagbard Emanuel Berner, and painter Erik Werenskiold.