The article deals with important issues in general linguistic theory discussed by Mikołaj Habdank Kruszewski alias Nikolaj Vjačeslavovič Kruševskij (1851–1887), in the author’s view an unjustly forgotten linguist of genius of the late 19th century, who could be seen as standing at the roots of the 20th-century structuralism, long before the appearance of F. de Saussure’s lectures on general linguistics. In his major book O čerk nauki o jazyke (An outline of the science of language) of 1883, Kruszewski conceived of language as a system of signs, laying stress on the semiotic function of language. His understanding of sound alternation is in many ways close to modern principles of phonology and morphonology. His hypothesis of the universal character of the sound laws too anticipated the discovery of language universals. As a result, the author agrees with Radwańska-Williams’ (1993) characterization of Kruszewski’s theory as ‘a lost paradigm’ in the history of linguistics. Well-known linguists of the 20th century such as Roman Jakobson (1896–1982), Jerzy Kuryłowicz (1895–1978) , and others rightly argued that Kruszewski was one of the founders of modern linguistic theory.