On the Unchangeableness of God (41-45)

And the Creator has made the soul to differ from nature in these things—in the outward sense, and imagination, and impetuosity; for plants are destitute of impetuosity and devoid of imagination, and without any participation in the outward sense. But every animal partakes of all these qualities above-mentioned, all together.

Now the outward sense, as indeed its name shows, in some degree is a kind of insertion, placing the things that are made apparent to it in the mind; for in the mind, since that is the greatest store-house and receptacle for all things, is everything placed and treasured up which comes under the operation of the sense of seeing or hearing, or the other organs of the outward senses.

And imagination is an impression of figures in the soul; for the things which each of the outward senses has brought in, like a ring or a seal, on them it imprints its own character. And the mind, being like wax, having received the impression, keeps it carefully in itself until forgetfulness, the enemy of memory, has smoothed off the edges of the impression, or else has rendered it dim, or perhaps has completely effaced it.

And that which has been visible and has been impressed upon the soul at times affects the soul in a way consistent with itself, and at other times in a different way; and this passion to which it is subject is called appetite, which philosophers who define such things say is the first motion of the soul.

In such important points are animals superior to plants. Let us now see in what man is superior to the rest of the animal creation.