Note 98 — IX
Reading edition
The motive for making this assumption was clearly the desire to make of the Νοῦς the prime mover in the world while exempting it from reaction on the part of the world, which would have been unavoidable if its nature had contained parts of other things. It is the same problem of "touching without being touched in return" that led Aristotle to a similar definition of God and of the rational soul. The same difficulty besets the absolutely "simple" soul of Plato's Phaedo and the causality of the Ideas.