A language is by its aim first and foremost a sign system [...]. But, with all its limitless abundance, in order to be fully adequate, a language must likewise be easy to manage, practical in acquisition and use. Under the requirement of an unrestricted number of signs, this can be achieved by all the signs’ being constructed of non-signs whose number is restricted, and, preferably, severaly restricted.
- Hjelmslev (1961), a pag.46