 To fully understand La Forge’s discussion, it is helpful to keep in mind the overall argumentative strategy that he tries to push. In the THM, La Forge’s main task is to show that there is mind-body interaction and that this is not so difficult to understand—as many of Descartes’s opponents have claimed. The Cartesian account of mind-body interaction has been widely criticized because of the radical heterogeneity of thinking and extended substances in Descartes’s ontology. Elisabeth of Bohemia, for instance, provides a paradigmatic expression of this concern: