The ultimate law of language is, dare we say, that nothing can ever reside in a single term. This is a direct consequence of the fact that linguistic signs are unrelated to what they designate and that, therefore, 'a' cannot designate anything without the the aid of 'b' and vice versa, or, in other words, that both have value only by the difference between them.
Ferdinand de SaussureNearly all institutions, it might be said, are based on signs, but these signs do not directly evoke things.
Ferdinand de SaussureIt is one of the aims of linguistics to define itself, to recognise what belongs within its domain. In those cases where it relies upon psychology, it will do so indirectly, remaining independent.
Ferdinand de Saussure