Saussure's relational conception of meaning was specifically differential. He emphasized the differences between signs. Language for him was a system of functional differences and oppositions. 'In a language, as in every other semiological system, what distinguishes a sign is what constitutes it'. What gives the letter 'C' its meaning is its difference from other letters. The concept of difference turns very clear once we think it in terms of dress code. What makes a costume meaningful, fashionable, or respectable is its difference from other clothes. Advertising furnishes another good example of this notion, since what matters in 'positioning' a product is not the relationship of advertising signifiers to real-world referents, but the differentiation of each sign from the others to which it is related. In other words relation/difference is a pair of binary opposites. Saussure's concept of the relational identify of signs is at the heart of structuralist theory. Structuralist analysis focuses on the structural relations which are functional in the signifying system at a particular moment in history. 'Relations are important for what they can explain: meaningful contrasts and permitted or forbidden combinations'. We can safely conclude that 'in a language there are only differences'.