He did not write the Course in General Linguistics. Students of his wrote it from their notes of his lectures between 1906-1911. Linear Nature of the Signifier Auditory expression has duration and it is linear The mechanisms of language and language construction are dependent on this Linguistic Value Language as Organized Thought Coupled with Sound Thought is dependent on language. There can be no clearly distinct concept to think about without language.
Language creates a link between sound and idea.
Sounds by themselves don't have any real significance to thought. Linguistics combines thought and sound to produce a form, not a substance. The individual cannot create the arbitrary system alone. It requires agreement. The value of letters is negative and differential.