Soul arises as the idea and act of the motionless Intellectual-Principle — which itself sprang from its own motionless prior — but the soul’s operation is not similarly motionless; its image is generated from its movement. It takes fulness by looking to its source; but it generates its image by adopting another, a downward, movement.
This image of Soul is Sense and Nature, the vegetal principle.
Nothing, however, is completely severed from its prior. Thus the human Soul appears to reach away as far down as to the vegetal order: in some sense it does, since the life of growing things is within its province; but it is not present entire; when it has reached the vegetal order it is there in the sense that having moved thus far downwards it produces — by its outgoing and its tendency towards the less good — another hypostasis or form of being just as its prior (the loftier phase of the Soul) is produced from the Intellectual-Principle which yet remains in untroubled self-possession.