The aim of this contribution is to present the theory of intentionality proposed by the Spanish Dominican Lope de Barrientos (1382–1469), as it is offered by his Clavis Sapentiae: in this erudite work, written at the turn of the 15th century in the context of the new-born School of Salamanca, the terms proper to the gnoseological lexicon of the Thomist scholasticism are taken into consideration, analysed and renewed in a new original way. This makes possible to demonstrate from one hand how the tradition opened by Thomas Aquinas is inherited in the upcoming Renaissance and from another hand to look how a typical Renaissance scholar as Barrientos builds a theory of knowledge that is original, although faithful to the Thomist tradition to which it has been continuously and cogently referred and consulted.