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.
p. 16 ; Partly cited in; Geza Revesz, The Origins and Prehistory of Language, London 1956. p. 126 - Cours de linguistique générale (1916)