Note that, to Saussure, the ``signified'' is not the object itself. Rather, it is our concept of the object. The relationship between the concept and the object itself is also an arbitrary one. For example, we consider objects X, Y, and Z to be trees, not because they share some fundamental property that not-trees do not; but rather because we have defined the concept of a tree to include them and not other things. This example also illustrates another important part of Saussure's theory: language is inherently differential in nature. Just as X, Y, and Z are trees because they are not not-trees, the word `tree' refers to the concept of trees because it does not refer to not-trees.

Saussure's theory of general linguistics deals with the synchronic aspect of language, which it holds to be more important than the diachronic aspect. Likewise, it focuses on langue (the system of a language) over parole (the set of all speech occurences). General linguistics views language as a self-contained system---much as the New Critics viewed the Work as a self-contained system. Saussure is thus seen as an important precursor to 20th-century literary criticism.