Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

He theorized the existence of laryngeals while still a student, and he described the development of the vowel a in Memoir on the Original System of Vowels in the Indo-European Languages. He also developed the idea of the linguistic sign and signifier. His most influential work helped to establish structural linguistics; however, it was compiled and published by Charles Bally and Albert Sechehaye. That work distinguished langue from parole. For 10 points, name this Swiss guy whose notes were compiled into the posthumous Course in General Linguistics.
Social Science