Whether the Act of the Vegetal Soul Is Commanded?
Objection 1: It would seem that the acts of the vegetal soul are
subject to the command of reason. For the sensitive powers are of
higher rank than the vegetal powers. But the powers of the sensitive
soul are subject to the command of reason. Much more, therefore, are
the powers of the vegetal soul.
Obj. 2: Further, man is called a "little world" [*Aristotle,
_Phys._ viii. 2], because the soul is in the body, as God is in the
world. But God is in the world in such a way, that everything in the
world obeys His command. Therefore all that is in man, even the
powers of the vegetal soul, obey the command of reason.
Obj. 3: Further, praise and blame are awarded only to such acts as
are subject to the command of reason. But in the acts of the
nutritive and generative power, there is room for praise and blame,
virtue and vice: as in the case of gluttony and lust, and their
contrary virtues. Therefore the acts of these powers are subject to
the command of reason.
_On the contrary,_ Gregory of Nyssa [*Nemesius, De Nat. Hom. xxii.]
says that "the nutritive and generative power is one over which the
reason has no control."
_I answer that,_ Some acts proceed from the natural appetite, others
from the animal, or from the intellectual appetite: for every agent
desires an end in some way. Now the natural appetite does not follow
from some apprehension, as [d]o the animal and the intellectual
appetite. But the reason commands by way of apprehensive power.
Wherefore those acts that proceed from the intellective or the animal
appetite, can be commanded by reason: but not those acts that proceed
from the natural appetite. 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."
Consequently the acts of the vegetal soul are not subject to the
command of reason.
Reply Obj. 1: The more immaterial an act is, the more noble it is,
and the more is it subject to the command of reason. Hence the very
fact that the acts of the vegetal soul do not obey reason, shows that
they rank lowest.
Reply Obj. 2: The comparison holds in a certain respect: because, to
wit, as God moves the world, so the soul moves the body. But it does
not hold in every respect: for the soul did not create the body out
of nothing, as God created the world; for which reason the world is
wholly subject to His command.
Reply Obj. 3: Virtue and vice, praise and blame do not affect the
acts themselves of the nutritive and generative power, i.e.
digestion, and formation of the human body; but they affect the acts
of the sensitive part, that are ordained to the acts of generation
and nutrition; for example the desire for pleasure in the act of
taking food or in the act of generation, and the right or wrong use
thereof. ________________________