This chapter offers a historical and theoretical perspective. A comprehensive understanding of Saussure's ideas requires some idea of how other linguists at the time dealt with the same topics. Only in this way can the novelty of his theory become clear, a novelty of which contemporary linguists were not fully aware. The key notions that are addressed in this chapter - system, arbitrariness and value - are at the very heart of Saussure's objectives, and are abstract and theoretical, even more so than other concepts in the CLG.