But the soul which cannot be destroyed either by internal or external evil must be immortal and everlasting.

And if this be true, souls will always exist in the same number.

They cannot diminish, because they cannot be destroyed; nor yet increase, for the increase of the immortal must come from something mortal, and so all would end in immortality.

Neither is the soul variable and diverse; for that which is immortal must be of the fairest and simplest composition.
If we would conceive her truly, and so behold justice and injustice in their own nature, she must be viewed by the light of reason pure as at birth, or as she is reflected in philosophy when holding converse with the divine and immortal and eternal.

In her present condition we see her only like the sea-god Glaucus, bruised and maimed in the sea which is the world, and covered with shells and stones which are incrusted upon her from the entertainments of earth.
Thus far, as the argument required, we have said nothing of the rewards and honours which the poets attribute to justice; we have contented ourselves with showing that justice in herself is best for the soul in herself, even if a man should put on a Gyges' ring and have the helmet of Hades too.