The term metafunction originates in systemic functional linguistics and is considered to be a property of all languages.
Thus, the human species had to "make sense of the complex world in which it evolved: to classify, or group into categories, the objects and events within its awareness".
[7] In taking this position on the active role of grammar in construing "reality", Halliday was influenced by Whorf.
Language not only construes experience, but simultaneously acts out "the interpersonal encounters that are essential to our survival".
[10] Halliday argues that these encounters: The grammatical systems that relate to the interpersonal function include Mood, Modality, and Polarity.
These systems "create coherent text – text that coheres within itself and with the context of situation" [8] They are both structural (involving choices relating to the ordering of elements in the clause), and non-structural (involving choices that create cohesive ties between units that have no structural bond).
Through the textual function, language "creates a semiotic world of its own: a parallel universe, or 'virtual reality' in modern terms".