Speech has both an individual and a social side, and we cannot conceive of one without the other.
The characteristic role of language with respect to thought is not to create a material phonic means for expressing ideas but to serve as a link between thought and sound,
Time changes all things; there is no reason why language should escape this universal law.
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.