In this study an analyze the paroemias with the lexemes osh / osho ‘white’ and shem / sheme ‘black̕, including as part of semantic oppositions is performed. The research was carried out on the material of the national corpus of the Mari language, as well as materials from dictionaries, collections of folklore. The work describes the semantic content of the paroemias, provides a decoding of some cultural codes, and describes the value system of the Mari people. In the structure of the opposition to osho - sheme , in addition to the lexical semantics proper, evaluative semantics is actualized: osho ‘white’ embodies light, pure, real, true, sheme ‘black’ contains axiological components of the meaning ‘dark, evil, bad, joyless, heavy, harmful, oppressive’. The semantic opposition under consideration reflects the idea of unity of opposite principles: Osho pelen kech-kunamat sheme liesh ‘There is always black next to white.’ The opposition is interpreted ambiguously in the national consciousness: Sheme da sheremet, osho da keremet ‘Black but dear (cute), white but damn’, Shem shorykat osh pacham yshten kertesh ‘Even a black sheep can produce a white lamb’. The semantic opposition osho - sheme ‘white - black’ to a certain extent embodies the people’s worldview and perception, the assessment of reality.