Roman Jakobson greatly influenced the development of linguistic theory. He was a founder of and prime mover in the Prague Linguistic Circle. On the basis of the new structuralist concepts, he set forth bold theories of general linguistics and illustrated them with demonstrations based on Slavic and other languages. Taking a leading role in the elucidation of the structural linguistic field of phonology, Jakobson used these insights to develop new trends in historical phonology. Altogether, his linguistics appears to incorporate the technical design of modern theoretical concepts, but at the same time transcends purely formal modelling through its interdisciplinary focus upon historical and poetry matters. Jakobson was successful in presenting innovative theoretical insights and relating them to possible practical applications. Specifically, his work on the general processes of language aquisition and loss opened up new methods for linguists and doctors alike.