In the Vosmaer family archives (General State Archives, The Hague) are a few letters written by the painter Willem Roelofs to the man of letters Carel Vosmaer between 1863 and 1882. The letters indicate that Roclofs and Vosmaer were already on friendly terms while the former was living in Brussels. Six of the letters are quoted in full in this article. A letter of 1863 refers to a report drawn up by Vosmaer for Minister Thorbecke concerning the purchase of works of modern art for the government. In the same letter Roelofs intimates that his sojourn in Brussels was disappointing. In 1869 he endorsed the views expressed by Jozef Israels under a pseudonym in a magazine article, putting forward his (Israels') ideas about the modern artist's task as opposed to former, outdated notions. In his article, Israels advocated the depiction of visible reality instead of subjects clictated by literature and historical science. The article appeared in De Nederlandshz Spectator, of which Vosmaer was an editor. For another issue of the same journal that year Roelofs sketched a megalithic tomb in Tinaarlo (fig. 2), with a caption protesting at the destruction of such monuments. The following year Roelofs asked Vosmaer's advice on the establishment of a society for the cultivation of etching'. After the appearance of Vosmaer's biography of Roelofs in the magazine Eigen Haard in 1879, the painter apprised him in a letter of a few errors, providing important additional information about his artistic work and detailed study of beetles. Vosmaer incorporated this information in an issue of Onze hedendaagsche schilders devoted to Roelofs in 1882, for which the artist supplied the illustrations. A letter prompted by the galley proofs contains Roelofs' observations on a few technical aspects of his watercolours.