12. Extensions therefore contribute to the constitutions of bodies; for the forms of bodies are in extensions. These forms produce themselves not in extension (which is a form), but in the substrate that has received extension. If they occurred in extension, instead of occurring in matter, they would nevertheless have neither extension nor (hypostatic) substance; for they would be no more than reasons. Now as reasons reside in the soul, there would be no body. Therefore, in the sense-world, the multiplicity of forms must have a single substrate which has received extension, and therefore must be other than extension. All things that mingle form a mixture, because they contain matter; they have no need of any other substrate, because each of them brings its matter along with it. But (forms) need a receptacle (a residence), a "vase" (or stand), a location (this in answer to the objection at the beginning of the former section). Now location is posterior to matter and to bodies. Bodies, therefore, presuppose matter. Bodies are not necessarily immaterial, merely because actions and operations are. In the occurrence of an action, matter serves as substrate to the agent; it remains within him without itself entering into action; for that is not that which is sought by the agent. One action does not change into another, and consequently has no need of containing matter; it is the agent who passes from one action to another, and who, consequently, serves as matter to the actions (as thought Aristotle).[304] NOT EVEN CORPOREITY INHERES IN MATTER WHICH IS REACHED BY BASTARD REASONING.