It is remarkable that for eighty years the understanding of Saussure's thought has depended on an incomplete and non-definitive text, the sometimes aphoristic formulations of which gave rise to many creative interpretations and arguments for and against Saussure. Did he, or did he not, see language as a-social and a-historical? Did he, or did he not, rule out the study of speech within linguistics? Was he a reductionist? These disputes and many others can now be resolved on the basis of the work now published. This reveals new depth and subtetly in Saussure's thoughts on the nature and complex workings of language, particularly his famous binary oppositions between form and meaning, the sign and what is signified, and language (langue) and its performance (parole).