Of God and His Creatures
That the Souls of Dumb Animals are not Immortal
No activity of the sentient part can have place without a body. But in
the souls of dumb animals we find no activity higher than the
activities of the sentient part. That animals neither understand nor
reason is apparent from this, that all animals of the same species
behave alike, as being moved by nature, and not acting on any principle
of art: for every swallow makes its nest alike, and every spider its
web alike. Therefore there is no activity in the soul of dumb animals
that can possibly go on without a body.De Anima, III,
iv, 13). Therefore the soul of a dumb animal will have understanding,
which is impossible.* But they have not that craving consequent upon
apprehension: for since the sentient soul apprehends only what is here
and now, it cannot possibly apprehend perpetuity of being, and
therefore has no physical craving after such perpetuity.Arguments of those who wish to prove that the Human Soul perishes with the Body, with Replies to the same
2.83, 84 : Apparent Arguments to show that the Human Soul does not begin with the Body, but has been from Eternity, with Replies to the same