As the name suggests, the notion of "system" is a defining aspect of systemic functional linguistics. In linguistics, the term "system" can be traced back to Ferdinand de Saussure, who noticed the roughly corresponding paradigms between signifying forms and signified values. The paradigmatic principle of organization was established in semiotics by Saussure, whose concept of value (viz. "valeur") and of signs as terms in a system "showed up paradigmatic organization as the most abstract dimension of meaning". However, Halliday points out that "system" in the sense J.R. Firth and he himself used it was different from Saussure's. In their case, "system" does not stand for a list of signifying forms corresponding to a list of signified values. Instead, Firth and Halliday described systems as contrasting options in value realised by contrasting options in form where the options are not the entire form and the entire value but features thereof. In this sense, linguistic systems are a background for formal features, i.e. features of structure. Here, the most general linguistic system is human adult language itself since it is a system of options whereby humans choose whether to speak "in English", "in Chinese", "in Spanish" or in another variety of language. In this sense, language is a system ("the system of language") not only as proposed by Hjelmslev., but also as a system of options. In this context, Jay Lemke describes human language as an open, dynamic system, which evolves together with the human species.