In 1811, the Royal Danish Academy of Sciences and Letters put out a call for a prize essay on the topic of language history that would "use historical critique and fitting examples to illuminate the source whence the old Scandinavian tongue can be most probably derived, to explain the character of the language and the relations that it has had through the middle ages to the Nordic as well as Germanic dialects, and to accurately ascertain the basic tenets upon which all derivation and comparison of these tongues should be constructed." In order to conduct research for the prize essay, Rask traveled to Sweden in 1812 with his friend Rasmus Nyerup.There, he studied Sami and Finnish in order to determine whether they were related to the Scandinavian languages.In 1831, just a year before his death, he was hired as professor of Eastern languages at the University of Copenhagen.After his return to Denmark, Rask published Spanish Grammar (1824), Frisian Grammar (1825), Essay on Danish Orthography (1826), Treatise respecting the Ancient Egyptian Chronology (1827), Italian Grammar (1827), and Ancient Jewish Chronology previous to Moses (1828).Inscriptions in Arabic, Old Norse, Sanskrit and Danish.Translated to English, it reads: "If you wish to become perfect in knowledge, you must learn all the languages, and yet, do not neglect your native tongue or speech." Rask returned to Copenhagen in May 1823, bringing a considerable number of manuscripts in Persian, Zend, Pali and Sinhalese for Copenhagen libraries; in 1825, he was hired as a professor of literary history, and in 1829, he was hired as a librarian at the University of Copenhagen.Rask is especially known for his contributions to comparative linguistics, including an early formulation of what would later be known as Grimm's Law.
According to Hans Frede Nielsen, it exceeded anything previously published on the topic.
Soon afterwards, he wrote (in English) "A Dissertation respecting the best Method of expressing the Sounds of the Indian Languages in European Characters".
Rasmus Rask's grave at Assistens Cemetery, Copenhagen.
In 1820, he traveled from Bushehr, Persia to Mumbai, India (then called Bombay), and during his residence there, he wrote (in English) "A Dissertation on the Authenticity of the Zend Language" (1821).
From Bombay, he traveled through India to Sri Lanka (then called Ceylon), arriving in 1822.