  Languages, both object languages and metalanguages, are in the monograph not just interpreted grammars; a language also includes a deductive system. A Tarskian metalanguage always includes its object language as a part, both its grammar (perhaps under some translation) and its deductive system. And besides, it will always contain a few more things if these things are not already in the object language. Specifically, it will always contain a sub-language and sub-theory that can be used to say a great deal of things about the syntax of the object language; and it will always contain all the mathematics (both concepts and methods of proof) that “may be taken from any sufficiently developed system of mathematical logic” (Tarski 1983b, p. 211).