Writing obscures language ; it is not a guise for language but a disguise. - Ferdinand de Saussure

The subject matter of linguistics comprises all manifestations of human speech, whether that of savages or civilized nations, or of archaic, classical or decadent periods. In each period the linguist must consider not only correct speech and flowery language, but all other forms of expression as well. And that is not all: since he is often unable to observe speech directly, he must consider written texts, for only through them can he reach idioms that are remote in time or space.

Language is a system of signs that express ideas, and is therefore comparable to a system of writing, the alphabet of deaf-mutes, symbolic rites, polite formulas, military signals, etc. But it is the most important of all these systems.

The linguistic entity is not accurately defined until it is delimited, i.e. separated from everything that surrounds it on the phonic chain. These delimited entities or units stand in opposition to each other in the mechanism of language.