The aim of this contribution is the study of the concept of primae intentiones according to the Breton tomist Hervaeus Natalis (1250-1323), through the analysis of his Tractatus de secundis intentionibus. In this text, the Breton inherits the theory of knowledge of Thomas Aquinas to re-elaborate it in the light of the concept of intentio, making the Tractatus the first work in which the theory of intentionality is exposed in a unitary way. This paper will examine the first part of this theory, in which Hervaeus theorizes the primae intentiones as a medium by which an object of the world is known and ‘passes’ into the intellect of a knowing subject, to analyse its originality.