There is no need to prove that bodily nourishment cannot satisfy the soul of man, nor can bodily drink quench its thirst. But even all this spirit of life, that shines through all created things, giving them life and harmony, is incapable of feeding and refreshing the soul.
The body directly receives food that is in essentials identical to the body. The body is of the earth, and food for the body is of the earth. This is why the body feels at home, among its own, in the world. But the soul suffers; it is crucified and suffers; it is disgusted and protests at having to receive food indirectly, and this a food not identical to itself. The soul therefore feels itself, in this world, to be in a foreign country, among strangers.
That the soul is immortal, and that it, in its essence, belongs to the immortal world, is proved by the fact that, in this earthly world, it feels itself a discontented traveller in a foreign land, and that nothing in the world can fully feed and refresh it. And even were the soul to be able to pour the whole universe into itself like a glass of water, its thirst would not only not become less but would, of a certainty, become greater. For then there would not remain in it one single illusory hope that it would, beyond the next hill, light on an unsuspected source of water.