The view that living beings as well as plant-based medicaments possess causal properties that are caused by the causal properties of their constituents, without being reducible to the combination of the causal properties of these constituents goes back to ancient thinkers such as Alexander of Aphrodisias and Johannes Philoponus. In the early modern period, this view was not only criticized by natural philosophers taking a reductionist stance; it was also criticized by Neo-Platonic thinkers such as Jean Fernel. One of the (...) relatively few early modern natural philosophers who adopted an emergentist position was Jacob Schegk. The present article discusses whether Schegk’s analysis of the structure of plants and medicaments offers the theoretical resources required to answer Fernel’s critique of the tradition going back to Alexander. In particular, it examines whether Schegk’s account of synchronic upward causation and diachronic downward causation could offer solutions to two interrelated problems identified by Fernel: the question of whether a mere aggregates of material particles could form a composite that possesses substantiality, not only accidental unity; and the question of whether multitudes of material particles could bring forth simple forms, whose existence seems to be presupposed by powers that cannot be ascribed to the constituents. (shrink)