Apart from his numerous works in comparative linguistics, Rasmus Kristian Rask (1787–1832) is also the author of a manuscript in which he sets forth in detail his conception of a universal auxiliary language. Written during 1819–1820, this 72-page treatise, entitled Optegnelser til en Pasigraphie, has been neglected by linguistic research up to the present, in part because it remained in manuscript form. Rask’s draft of a planned language is divided into three sections: (1) The grammatical system and basic vocabulary; (2) numerous examples of word-formation, morphology etc. and (3) samples of texts. Rask deplores the waste of energy resulting from the multiplicity of languages in international communication. In his opinion, many intellectual achievements are lost or cannot be further developed owing to lack of exchange facilities. Instead of having to learn words and structures, people should be placed in a position to tackle the subject matter. The practical aim of linguistic studies should therefore be the creation of an international means of communication to be used in the field of science as well as in every-day life. Important postulates of such a conception would be: improved learnability by means of simplification of grammatical structures, consistency in word-formation and easy articulation for people of different language communities. To conform to these aims, Rask decided to create a system mainly on the basis of romance languages, i.e., Latin, Spanish, French and Portugese, complemented by Greek and English. Rask’s essay presents a hitherto unknown type of planned language, commonly described as ‘naturalistic’. Whereas other aposterioric systems like Esperanto give priority to regularity and logic and are therefore called ‘autonomous’, Rask tries to remain faithful to the results of historical evolution. In that respect, Rask’s project resembles Otto Jespersen’s ‘Novial’, which was to be conceived a century later.