If we disregard the study of language and turn directly towards things themselves, we condemn ourselves to project into being the shadow of the elements and articulations structuring language. Ockham undertakes, at the beginning of the 14th century, a critical analysis of logical categories inherited from Aristotle, Porphyre and Boèce. This analysis do not lead to an imprisonment into language, but, on the contrary, to a rigourous study of the relationship between verbal (or conceptual) signs and singular things which really exist. That is to say that the first treatise of Summa logicae is stipulating principles for semantical analysis and that Ockham’s logic is a chief work in order to understand the late medieval philosophy : It splits with the view which was prevailing before, and reasserts, against the Augustinian claim of a cosmological system made of symbolic connections, the face to face relationship between the real world and language as a structured set of signs.