It has been shown in Part III (n. 173-176) that there are three atmospheres both in the spiritual and the natural world, which are distinguished from each other according to degrees of height, and which in their progress towards lower things decrease according to degrees of breadth. And because atmospheres decrease in their progress towards lower things, it follows that they continually become more dense and inert, and finally in ultimates, become so dense and inert as to be no longer atmospheres, but substances at rest, and in the natural world fixed like those on the earth called matters. From this origin of substances and matters it follows, first, that these substances and matters are also of three degrees; secondly, that they are held together in mutual connection by the surrounding atmospheres; thirdly, that they are accommodated to the production of all uses in their forms.