to take the life of any
living thing.

Obj. 2: Further, murder is a sin because it deprives a man of life.
Now life is common to all animals and plants. Hence for the same
reason it is apparently a sin to slay dumb animals and plants.

Obj. 3: Further, in the Divine law a special punishment is not
appointed save for a sin. Now a special punishment had to be
inflicted, according to the Divine law, on one who killed another
man's ox or sheep (Ex. 22:1). Therefore the slaying of dumb animals
is a sin.

_On the contrary,_ Augustine says (De Civ. Dei i, 20): "When we hear
it said, 'Thou shalt not kill,' we do not take it as referring to
trees, for they have no sense, nor to irrational animals, because
they have no fellowship with us. Hence it follows that the words,
'Thou shalt not kill' refer to the killing of a man."

_I answer that,_ There is no sin in using a thing for the purpose for
which it is. Now the order of things is such that the imperfect are
for the perfect, even as in the process of generation nature proceeds
from imperfection to perfection. Hence it is that just as in the
generation of a man there is first a living thing, then an animal,
and lastly a man, so too things, like the plants, which merely have
life, are all alike for animals, and all animals are for man.
Wherefore it is not unlawful if man use plants for the good of
animals, and animals for the good of man, as the Philosopher states
(Polit. i, 3).

Now the most necessary use would seem to consist in the fact that
animals use plants, and men use animals, for food, and this cannot be
done unless these be deprived of life: wherefore it is lawful both to
take life from plants for the use of animals, and from animals for
the use of men. In fact this is in keeping with the commandment of
God Himself: for it is written (Gen. 1:29, 30): "Behold I have given
you every herb . . . and all trees . . . to be your meat, and to all
beasts of the earth": and again (Gen. 9:3): "Everything that moveth
and liveth shall be meat to you."

Reply Obj. 1: According to the Divine ordinance the life of animals
and plants is preserved not for themselves but for man. Hence, as
Augustine says (De Civ. Dei i, 20), "by a most just ordinance of the
Creator, both their life and their death are subject to our use."

Reply Obj. 2: Dumb animals and plants are devoid of the life of
reason whereby to set themselves in motion; they are moved, as it
were by another, by a kind o