Abstract

The article aims to show how in some of Leibniz's texts a mathematical invention, the theory of envelopes, can to a certain extent be seen as a model for one of his key metaphysical contributions, namely the theory of inter-expression ("entr'expression"). First, we examine two of Leibniz's articles in the Acta Eruditorum (1692 and 1694) where this mathematical object is introduced. Next, we analyze the notion of inter-expression, which reveals a striking structural similarity with the mathematical invention mentioned above. We then suggest that inter-expression requires a different model from that of mere expression. The fundamental issue is to determine to what extent we can use the concept of model in this case and, if so, what its philosophical significance is. More broadly, it is an opportunity to consider the relationship between mathematics and metaphysics in Leibniz's philosophy, which may well have never been as closely connected as they are in this case