... language, as an example of a semiotic system, contains all four levels of organization as follows:
First, it is transmitted physically, by sound waves traveling through the air; secondly, it is produced and received biologically, by the human brain and its associated organs of speech and hearing; thirdly it is exchanged socially, in contexts set up and defined by the social structure; and fourthly it is organized semiotically as a system of meanings
M.A.K. Halliday (2006, p. 68) as cited in: Andrew Halliday and Marion Glaser (2011).
