“(and even all the forms of inanimate bodies) can be explained without the need of supposing for that purpose anything in their matter other than the motion, size, shape, and arrangement of its parts” (The World, Chapter 5). Accordingly, Descartes does not need substantial forms and does not explain mutation as change of form, whether substantial or accidental. He finds no forms other than the ones he has described quantitatively. For Descartes, the only motion is local motion; hence he states, “The philosophers also suppose several motions that they think can be accomplished without any body changing place…. As for me, I know of none except the one which is easiest to conceive …, the motion by which bodies pass from one place to another” (The World, Chapter 7).”