In 1902 he received his doctorate for a study of the historical phonetics of Turkish, after which he began teaching at the university, first as a docent and then from 1908 to 1911 as a lecturer in English literature, while also working as a church organist.
After the appearance of the remaining three volumes of Vor Folkeætt i Oldtiden in 1912 and of a related essay, "Religionsskiftet i Norden" on the conversion of Scandinavia (1913), the University of Leipzig sought in 1914 to award him a professorship and in 1915 he was appointed professor of the history of religion at Copenhagen, a position which he held until 1943.
[1] Grønbech was married twice, in 1900 to Pauline Ramm, who died in 1946, and in August 1947 to Honorine Louise Hermelin, rector of the Swedish folk high school for women at Fogelstad in Sweden.
[1][8] Although trained as a philologist, Grønbech's focus from his earliest major work, Vor Folkeætt i Oldtiden, was on analysing key terms in order to apprehend the essence of a religion and hence of a culture.
He was unusually capable of immersing himself in the system of thought he wished to depict,[1] such that in the words of his English-language biographer he could "write about [it] as if he accepted its theses and principles", and "it is not possible to circumscribe accurately what his own religious—not to mention political—convictions must have been.
"[10][11] The admission of multiple realities (but only one actuality) is a leitmotiv in his work,[12] and he gave his second collection of poems, published in 1941, the title Solen har mange veje (The Sun Has Many Paths).
[15] This openness combined with his heavy use of paraphrase can make it hard to distinguish his own position from those of the thinkers he is depicting, for example in his presentation of Empedocles' thought in Hellas, Volume 4.
[32] His writings and in particular Frie Ord have often been said to have been the impetus for the establishment of Heretica, an influential literary journal published from 1948 to 1953;[3] the third issue contains three articles written in tribute to him following his death, of which that by the poet and co-editor Thorkild Bjørnvig is titled "The Heretic".