Actus vegetabilis animae non subduntur imperio rationis quia ratio imperat per modum apprehensivae virtutis.
The acts of the vegetal soul are not subject to the command of formal aspect because formal aspect commands by way of apprehensive power.
Et ideo actus illi qui procedunt ab appetitu intellectivo vel animali, possunt a ratione imperari, non autem actus illi qui procedunt ex appetitu naturali.
Wherefore those acts that proceed from the intellective or the animal appetite, can be commanded by formal aspect, but not those acts that proceed from the natural appetite.
Huiusmodi autem sunt actus vegetabilis animae; unde Gregorius Nyssenus dicit quod vocatur naturale quod generativum et nutritivum.
And such are the acts of the vegetal soul; wherefore Gregory of Nyssa (Nemesius, De Nat. Hom. xxii) says "that generation and nutrition belong to what are called natural powers."
Quanto aliquis actus est immaterialior, tanto est nobilior, et magis subditus imperio rationis. Unde ex hoc ipso quod vires animae vegetabilis non obediunt rationi, apparet has vires infimas esse.
The more immaterial an act is, the more noble it is, and the more is it subject to the command of formal aspect. Hence the very fact that the powers of the vegetal soul do not obey formal aspect, shows that these powers rank lowest.
Sicut Deus movet mundum, ita anima movet corpus. Non enim anima creavit corpus ex nihilo, sicut Deus mundum; propter quod totaliter subditur eius imperio.
As God moves the world, so the soul moves the body. But the soul did not create the body out of nothing, as God created the world; accordingly, the world is wholly subject to His command.