 Desgabets subscribed completely to the Cartesian doctrine of matter as a substance extended in length, width, and breadth. It was posited against the prevailing Peripatetic view that posits prime matter and substantial forms in order to explain the permanence underlying the continuous change that matter undergoes. On Descartes’s view, the essence of matter is its extension in three dimensions, and all of its changing attributes, properties and modes, such as movement, rest, figure, situation and composition of parts, are completely dependent upon and follow from this unified extension (OPD 2: 27). Matter, or corporeal substance, is clearly known when it is viewed as the geometrical object of mathematicians, as a magnitude extended in length, width and breadth.  Likewise, corporeal bodies are best viewed as the movements, rest, figures, arrangements and sizes of which corporeal substance is capable, and which, in its various diversifications and assemblages, “… now pass for the form of all particular bodies of which the world is composed” (OPD 1: 3). And, in all of this, “… there is nothing which is not governed by the laws of mechanics” (OPD 2: 4).