Descartes’ criterion for determining whether a function belongs to the body or soul was as follows: “anything we experience as being in us, and which we see can also exist in wholly inanimate bodies, must be attributed only to our body. On the other hand, anything in us which we cannot conceive in any way as capable of belonging to a body must be attributed to our soul. Thus, because we have no conception of the body as thinking in any way at all, we have reason to believe that every kind of thought present in us belongs to the soul. And since we do not doubt that there are inanimate bodies which can move in as many different ways as our bodies, if not more, and which have as much heat or more […], we must believe that all the heat and all the movements present in us, in so far as they do not depend on thought, belong solely to the body” (AT XI:329, CSM I:329).