The ladder is set up on the earth and extends into the celestial realm, the rungs on the ladder are the four elements or seven celestial bodies, and the angels ascending and descending are the celestial intelligences.
Moreover, the distinction between corporeal and incorporeal substances introduces the reader to the existence of celestial intelligences; the incorporeal simple substances that play a central role in his thought.
While the highest celestial intelligences are wholly separated from the material cosmos, demonic substances, albeit incorporeal, can affect the corporeal world through forces (vires) and influences (influxus) of various kind.
They explained the motions of the various nested spheres in terms of the materials of which they were made, external movers such as celestial intelligences, and internal movers such as motive souls or impressed forces.
They attempted to explain the spheres' motions in terms of the materials of which they were thought to be made, external movers such as celestial intelligences, and internal movers such as motive souls or impressed forces.
The distinction also explains the derivation of celestial souls and bodies from supernal intelligences: in this respect emanation is nothing but the exposition of the dialectic between necessary existence and possible essence, which together constitute the intelligences' being.
There are three kinds of intellects that exist through their essence: the separated intelligences, celestial bodies, and human intellects.
Although many scholastics continued to maintain that intelligences were the celestial movers, they now associated the intelligences with the planets themselves, rather than with the celestial spheres.
To think of the cosmos in terms of a living animal or the heavens in terms of celestial orbs moved by intelligences is anathema to Valla (as it was to many medieval scholastics as well).
In some of his writings, Siger teaches that God as the first being creates only one being immediately, the first immaterial substance, from which emanate the other intelligences, the celestial spheres and finally the sublunar world, in an eternal and necessary process.
