2 Corinthians 3:5-6
3 Since then It has given us life, let us remain living and not return again to the former deadness: for “Christ dies no more; for the death that He died, He died unto sin once:” and He will not have us always saved by grace: for so we shall be empty of all things. Wherefore He will have us contribute something also from ourselves. Let us then contribute, and preserve to the soul its life. And what is life in a soul, learn from the body. For the body too we then affirm to live, when it moves with a healthy kind of motion; but when it lies prostrate and powerless, or its motions are disorderly, though it retain the semblance of life or motion, such a life is more grievous than any death: and should it utter nothing sane but words of the crazy, and see one object instead of another, such a man again is more pitiable than those who are dead.
So also the soul when it has no healthiness, though it retain a semblance of life, is dead: when it does not see gold as gold but as something great and precious; when it thinks not of the future but crawls upon the ground; when it does one thing in place of another. For whence is it clear that we have a soul? Is it not from its operations? When then it does not perform the things proper to it, is it not dead? When, for instance, it has no care for virtue, but is rapacious and transgresses the law; whence can I tell that you have a soul?
Because you walk? But this belongs to the irrational creatures as well. Because you eat and drinkest? But this too belongs to wild beasts. Well then, because you stand upright on two feet? This convinces me rather that you are a beast in human form. For when you resemble one in all other respects, but not in its manner of erecting itself, thou dost the more disturb and terrify me; and I the more consider that which I see to be a monster. For did I see a beast speaking with the voice of a man, I should not for that reason say it was a man, but even for that very reason a beast more monstrous than a beast.
Whence then can I learn that you have the soul of a man, when you kick like the ass, when you bear malice like the camel, when you bite like the bear, when you devour like the wolf, when you steal like the fox, when you are wily as the serpent, when you are shameless as the dog? Whence can I learn that you have the soul of a man? Will ye that I show you a dead soul and a living? Let us turn the discourse back to those men of old; and, if you will, let us set before us the rich man [in the story] of Lazarus, and we shall know what is death in a soul; for he had a dead soul, and it is plain from what he did.
For, of the works of the soul he did not one, but ate and drank and lived in pleasure only. Such are even now the unmerciful and cruel, for these too have a dead soul as he had. For all its warmth that flows out of the love of our neighbor has been spent, and it is deader than a lifeless body. But the poor man was not such, but standing on the very summit of heavenly wisdom shone out; and though wrestling with continual hunger, and not even supplied with the food that was necessary, neither so spoke he anything of blasphemy against God, but endured all nobly.
Now this is no trifling work of the soul; but a very high proof that it is well-strung and healthful. And when there are not these qualities, it is plainly because the soul is dead that they have perished. Or, tell me, shall we not pronounce that soul dead which the Devil falls upon, striking, biting, spurning it, yet has it no sense of any of these things, but lies deadened nor grieves when being robbed of its wealth; but he even leaps upon it, yet it remains unmoved, like a body when the soul is departed, nor even feels it?
For when the fear of God is not present with strictness, such must the soul needs be, and then the dead more miserable. For the soul is not dissolved into corruption and ashes and dust, but into things of fouler odor than these, into drunkenness and anger and covetousness, into improper loves and unseasonable desires. But if you would know more exactly how foul an odor it has, give me a soul that is pure, and then you will see clearly how foul the odor of this filthy and impure one.
For at present you will not be able to perceive it. For so long as we are in contact habitually with a foul odor, we are not sensible of it. But when we are fed with spiritual words, then shall we be cognizant of that evil. And yet to many this seems of no importance. And I say nothing as yet of hell; but let us, if you will, examine what is present, and how worthy of derision is he, not that practises, but that utters filthiness; how first he loads himself with contumely; just as one that sputters any filth from the mouth, so he defiles himself.
For if the stream is so impure, think what must be the fountain of this filth! “for out of the abundance of the heart the mouth speaks.” Yet not for this alone do I grieve, but because that to some this does not even seem to be reckoned among improper things. Hence the evils are all made worse, when we both sin, and do not think we even do amiss.
Source: Homilies on Second Corinthians (New Advent)