This linguistic method shows the scope of confusion created by languages which cannot differentiate between existential be and copula. It manifests, for instance, that the main theme of Heidegger's "Being and Time" is "astī" (is-ness) rather than "hastī" (existence). When, in the beginning of his book, Heidegger claims that people always talk about existence in their everyday language, without knowing what it means, the example he resorts to is: "the sky "is" blue" which in Persian can be ONLY translated with the use of the copula "ast", and says nothing about "being" or "existence".