The aim of this article is to establish if the mathematical rationality of Marin Mersenne (1588-1648) leads necessarily to an univocity. Indeed, can human beings know the Pythagoras theorem in the same manner as God? In order to answer this question, we study the conception of truth as conformitas, considering its ideological and epistemological aspects. Then, we analyse the notion of possibles as the subject matter of mathematics and of the divine intellect. Last but not least, we put into question Jean-Luc Marion’s interpretation or radical univocity. Finally, we expose the results and take a position in this discussion.