J.R.R. Tolkien’s Oxford academic specialty was philology.
Philology is the historical study of languages and written texts, especially how languages develop and how older works can be interpreted. Tolkien’s expertise included Old English, Middle English, Old Norse, Welsh, Finnish, and other languages or literary traditions that influenced his creative work.
He became a professor of Anglo-Saxon at Oxford in 1925 and later Rawlinson and Bosworth Professor of Anglo-Saxon. In 1945 he moved to Merton College as Merton Professor of English Language and Literature, a position he held until his retirement in 1959.
Tolkien’s philological training helped him construct believable languages and cultures for Middle-earth. His invented languages were not random collections of unusual words: many had sound patterns, grammar, historical relationships, and writing systems. His fiction was also shaped by medieval works such as Beowulf, the Norse sagas, and the Finnish Kalevala.