This paper purports to present a second sample Indian vernacular - the Dakota of the Middle West - additional to the Hopi of Arizona, paradigm of the Whorf controversy. It tends to confirm Whorf's proposition that the polysynthesis of Indian languages is of a quite particular character - provided account is taken of the total aspect of language and not only of words denoting time and space. Its richness of vocabulary, its suppleness of grammar, its metaphorical tinge and its passivity - all of these criteria put Dakota on a level differing from Indo-European. An investigation of time conceptions provides further proof of this extraordinary distance from Standard Average European. Judging on the basis of Dakota there is much to be said in support of Whorf's proposition.