Abstract
The author describes the use of German in Jakub Deml´s texts from the beginning of his work until 1937. First the linguistic explanations which underline the role of the cognitive foundation and code switching in communication are discussed, and then Deml´s family language situation is described.
Experience with foreign languages which can 'save' or 'kill' is analysed according to his life and work. The majority of the article is a study of Deml´s works Zapomenuté světlo and Píseň vojína šílence, which contain significant parts written in foreign languages.
Deml´s relationship with German is described and discussed. The role of his native language and foreign languages in communication is introduced.