The article discusses the problem of the universal character of conceptual metaphors. Metaphors are viewed as the main instrument which enables a language to express new meanings. Metaphors are regarded in their connection with an abstract thinking, therefore it is argued that metaphors are not language tools only, but also tools of thought. It is shown that metaphors constitute an important cognitive mechanism which determines the heuristic function of the language. Fundamental differences between metaphor and metonymy, metaphor and comparison are displayed. The close connection of metaphor with abstract thinking determines its relative weight in different types of discourse, and in different languages. The latter depends on the domains of a particular language usage.