True, I said; if the inherent natural vice or evil of the soul is unable to kill or destroy her, hardly will that which is appointed to be the destruction of some other body, destroy a soul or anything else except that of which it was appointed to be the destruction.

Yes, that can hardly be.

But the soul which cannot be destroyed by an evil, whether inherent or external, must exist for ever, and if existing for ever, must be immortal?

Certainly.

That is the conclusion, I said; and, if a true conclusion, then the souls must always be the same, for if none be destroyed they will not diminish in number. Neither will they increase, for the increase of the immortal natures must come from something mortal, and all things would thus end in immortality.