hidden cause, so when its actuality has temporarily been destroyed, that work will return again to the place from which it came. Because of these facts,51 astronomers (mathematici) have divided the world into two parts: into that, namely, which stretches above the sphere of the moon and that which lies below it.52 The superlunary world, because in it all things stand fixed by primordial law, they called “nature,”53 while the sublunary
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