In the last two decades of his career, Saussure continually tried to clarify the status of signs, considering however that it was an “absurd task” attacking this “odd entity” consisting of the association of two heterogeneous species. In his Course II, Saussure showed that the semiological character of this entity does not derive from the properties of the material used but from the differential relations that this entity has with other coexisting entities. Previously, in the notes of La double essence, he had demonstrated that the internal link on which signs are based is “of a highly peculiar kind”, that is to say, totally unnatural. In this paper, we show the very important theoretical and methodological implications of this reversal of perspective, which consists in posing the psychic associative union in its entirety.