This paper deals with the relation that Descartes points between his system and concepts of matter and form from Aristotelian scholasticism. The resemblance arises when Descartes treats interaction among substances in correspondences with Elisabeth, Gassendi and Arnauld. Beginning with the example of the scholastic concept of weight, used many times by Descartes, this article traces an identity between concepts of form in Thomas Aquinas and of thought in Descartes, as well as traces his criticism on the concept of form, understood as hidden qualities, to inanimate bodies. Finally, this paper investigates Cartesian occasionalism as well as the importance of celestial movements for a better comprehension of nature in Thomas Aquinas.56131 173189