This study consists in a commentary on some passages from Avicenna, which deal with the category of the relative. The commentary points out the promotion of the relative to the role of an exclusive determining factor. An attempt is made here to show how Avicenna tries to detach the relative accident from its subject, in order to transform it into the exclusive determining factor of a pure thingness. The relative determination of this thingness must be able to receive specifications, which may extend as far as the infimae species. These specifications are obtained by the consideration of the other attributes of the subject of the relative attribution, which are henceforth no more than the “modes of advent” of the relation.