Phaedo - P:105

Answer me then, he sais, what is it that, present in a body, makes it living? -- A soul.

And is that always so? --Of course.

Whatever the soul occupies, it always brings life to it? -- It does.

Is there, or is there not, an opposite to life? -- There is.

What is it? -- Death.

So the soul will never admit the opposite of that which it brings along, as we agree from what has been said?

Most certainly, said Cebes.

Well, and what do we call that which does not admit the form of the even? -- The uneven.

What do we call that which will not admit the just and that which will not admit the musical?

The unmusical, and the other the unjust.

Very well, what do we call that which does not admit death?

The deathless, he said.

Now the soul does not admit death? -- No.

So the soul is deathless? -- It is.

Very well, he said. Shall we say that this has been proved, do you think?

Quite adequately proved, Socrates.