Ferdinand de Saussure (1857–1913), the founding figure of modern linguistics, made his mark on the field with a book he published a month after his 21st birthday, in which he proposed a radical rethinking of the original system of vowels in Proto-Indo-European. A year later, he submitted his doctoral thesis on a morpho-syntactic topic, the genitive absolute in Sanskrit, to the University of Leipzig. He went to Paris intending to do a second, French doctorate, but instead he was given responsibility for courses on Gothic and Old High Gerrman at the École Pratique des Hautes Études, and for managing the publications of the Société de Linguistique de Paris. He abandoned more than one large publication project of his own during the decade he spent in Paris. In 1891 he returned to his native Geneva, where the University created a chair in Sanskrit and the history and comparison of languages for him. He produced some significant work on Lithuanian during this period, connected to his early book on the Indo-European vowel system, and yielding Saussure’s Law, concerning the placement of stress in Lithuanian. He undertook writing projects about the general nature of language, but again abandoned them. In 1907, 1908–1909, and 1910–1911, he gave three courses in general linguistics at the University of Geneva, in which he developed an approach to languages as systems of signs, each sign consisting of a signifier (sound pattern) and a signified (concept), both of them mental rather than physical in nature, and conjoined arbitrarily and inseparably. The socially shared language system, or langue, makes possible the production and comprehension of parole, utterances, by individual speakers and hearers. Each signifier and signified is a value generated by its difference from all the other signifiers or signifieds with which it coexists on an associative (or paradigmatic) axis, and affected as well by its syntagmatic axis. Shortly after Saussure’s death at 55, two of his colleagues, Bally and Sechehaye, gathered together students’ notes from the three courses, as well as manuscript notes by Saussure, and from them constructed the Cours de linguistique générale, published in 1916. Over the course of the next several decades, this book became the basis for the structuralist approach, initially within linguistics, and later adapted to other fields. Saussure left behind a large quantity of manuscript material that has gradually been published over the last few decades, and continues to be published, shedding new light on his thought.