In this paper, we first try to understand how Saussure, in order to write his ideas on language, switches from an argumentative form to an entirely opposite one: he passes from the form found in the Science of Language to the disjointed form of the Item Notes. By pointing out some of the content differences between these two attempts at writing, the Item Notes are then detached from the Science of Language project and related to the Semiology introduction. As a final point, organising the links between the different research projects of this period grants a reconstruction of the theoretical path followed by Saussure between 1891 and 1911. This path reveals how central for Saussure’s thought was the semiological change, which turns out to be the originality basis of his linguistic proposals.