2 But who says it, and to whom says he it? What shall we say, brethren? Is it the flesh that says, “Praise thou the Lord, O my soul”? And can the flesh suggest good counsel to the soul? However much the flesh be conquered, and subjected as a servant to us through strength which the Lord imparts, that it serve us entirely as a bond slave, enough for us that it hinder us not....For the body, inasmuch as it is the body, is even beneath the soul; and every soul, however vile, is found more excellent than the most excellent body.
And let not this seem to you to be wonderful, that even any vile and sinful soul is better than any great and most surpassing body. It is better, not in deserts, but in nature. The soul indeed is sinful, is stained with certain defilements of lusts; yet gold, though rusted, is better than the most polished lead. Let your mind then run over every part of creation, and you will see that what we are saying is not incredible, that a soul, however blameable, is yet more praiseworthy than a praiseworthy body.
There are two things, a soul and a body. The soul I chide, the body I praise: the soul I chide, because it is sinful; the body I praise, because it is sound. Yet it is in its own kind that I praise the soul, and in its own kind that I blame the soul: and so in its own kind I praise the body, or blame it. If you ask me which is better, what I have blamed or what I have praised, wondrous is the answer you will receive....So you speak of the best horse and the worst man: yet you prefer the man you find fault with to the horse you praise.
The nature of the soul is more excellent than the nature of the body: it surpasses it by far, it is a thing spiritual, incorporeal, akin to the substance of God. It is somewhat invisible, it rules the body, moves the limbs, guides the senses, prepares thoughts, puts forth actions, takes in images of countless things; who is there, in short, beloved brethren, who may suffice for the praises of the soul? And yet such is the grace given to it, that this man says, “Praise the Lord, O my soul.”...It is not the flesh that says it.
Let the body be angel-like, still it is inferior to the soul, it cannot give advice to its superior. The flesh when duly obedient is the handmaid of the soul: the soul rules, the body obeys; the soul commands, the body performs; how then can the flesh give this advice to the soul? Is it then perchance the soul herself, who says to herself, and in a manner commands herself, and exhorts and asks herself? For through certain passions in one part of her nature she wavered; but in another part, which they call the reasonable mind, the wisdom whereby she thinks, clinging to God, and now sighing towards Him, she perceives that certain inferior parts of her are troubled by worldly emotions, and by a certain excitement of earthly desires, betake them to outward things, leaving God who is within; so she recalls herself from things outward to inward, from lower to higher, and says, “Praise the Lord, O my soul.”...The soul itself gives itself counsel from the light of God by the reasonable mind, whereby it conceives the wisdom fixed in the everlasting nature of its Author.
It reads there of somewhat to be feared, to be praised, to be loved, to be longed for, and sought after: as yet it grasps it not, it comprehends it not; it is, as it were, dazzled with brightness; it has not strength to abide there. Therefore it gathers itself, as it were, into a sound state, and says, “Praise the Lord, O my soul.”...And then the soul, weighed down, as it were, and unable to stand up as is fitting, answers the mind, “I will praise the Lord in my life”. What is, “in my life”? Because now I am in my death. Therefore first encourage yourself, and say, “Praise the Lord, O my soul.” Your soul answers you, I do praise so far as I can, slightly, poorly, weakly. Wherefore? Because, “while we are in the body, we are absent from the Lord.”...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)