 Also in the correspondence, Elisabeth shows herself to have a keen interest in the workings of the physical world and in efficient causal explanations of natural phenomena: she criticizes Kenelm Digby’s reading of Descartes; she requests the works of Hogelande and Regius; she reports on various observed phenomena, and in particular on diseases and cures, while looking for acceptable efficient causal explanations of them. This commitment efficient causal explanations leads her to try to disseminate Cartesian physics in Germany.