As long as the activity of linguists was limited to comparing one language with another, this general utility cannot have been apparent to most of th… - Ferdinand de Saussure

Language can be compared to a sheet of paper: thought is its recto and sound its verso: one cannot cut the verso without simultaneously cutting the recto. Similarly, in the matter of language, one can separate neither sound from thought nor thought from sound; such separation could be achieved only by abstraction, which would lead either to pure psychology, or to pure phonology.

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, under conditions that of necessity bring about the reciprocal delimitations of units. Thought, chaotic by nature, has to become ordered in the process of its decomposition. Neither are thoughts given material form nor are sounds transformed into mental entities; the somewhat mysterious fact is rather that "thought-sound" implies division, and that language works out its units while taking shape between two shapeless masses. Visualize the air in contact with a sheet of water; if the atmospheric pressure changes, the surface of the water will be broken up into a series of divisions, waves; the waves resemble the union or coupling of thought with phonic substance.

La langue est un systéme dont toutes les parties peuvent et doivent être considérés dans leur solidarité synchronique.