That is quite a good distinction between parole and langue that Saussure makes
You might want to read Saussure's book, belMarduk. It's quite accessible and available in any fine bookstore or library. The Cours was put together and published psothumously by a couple of Saussure's students. In the PIE world, he's known for his brilliant Mémoire sur le système primitif des voyelles dans les langues indo-europeennes written when he was in his early twenties. In it he hypothesized the existence of some phonemes (called laryngeals) in PIE that had not survived in any of the then-known IE daughter languages. Later in the 20th century, with the decipherment of Hittite, a phoneme was discovered where he said a laryngeal would be. Saussure is usually considered to be the father of structuralism, which started out in linguistics and spread from there to other disciplines.
