18 “Because You have rescued my soul from death, my eyes from tears, and my feet from slipping: that I may be pleasing before God in the light of the living”. With reason he is not pleasing to alien sons, that are put afar off from holy men, because they have not the light of the living, whence they may see that which to God is pleasing. “Light of the living,” is light of the immortal, light of holy men. He that is not in darkness, is pleasing in the light of the living.
A man is observed, and the things which belong to him; no one knows of what sort he is: God sees of what sort he is. Sometimes even the devil himself he escapes; except he tempt, he finds not: just as concerning that man of whom just now I have made mention:...“Does Job by any means worship God for nought?” For this was true light, this the light of the living, that gratis he should worship God. God saw in the heart of His servant His gratuitous worship. For that heart was pleasing in the sight of the Lord in the light of the living: the devil's sight he escaped, because in darkness he was.
God admitted the tempter, not in order that He might Himself know that which He did know, but in order that to us to be known and imitated He might set it forth. Admitted was the tempter; he took away everything, there remained the man bereft of possessions, bereft of family, bereft of children, full of God. A wife certainly was left. Merciful do ye deem the devil, that he left him a wife? He knew through whom he had deceived Adam....With wound smitten from head even unto feet, whole nevertheless within, he made answer to the woman tempting, out of the light of the living, out of the light of his heart: “you have spoken as though one of the unwise women,” that is, as though one that has not the light of the living.
For the light of the living is wisdom, and the darkness of unwise men is folly. You have spoken as though one of the unwise women: my flesh you see, the light of my heart you see not. For she then might more have loved her husband, if the interior beauty she had known, and had beheld the place where he was beautiful before the eyes of God: because in Him were vows which he might render of praise to God. How entirely the enemy had forborne to invade that patrimony! How whole was that which he was possessing, and that because of which yet more to be possessed he hoped for, being to go on “from virtues unto virtue.” Therefore, brethren, to this end let all these things serve us, that God gratis we love, in Him hope always, neither man nor devil fear.
Neither the one nor the other does anything, except when it is permitted: permitted for no other reason can it be, except because it does profit us. Let us endure evil men, let us be good men: because even we have been evil. Even as nothing God shall save men, of whom we dare to despair. Therefore of no one let us despair, for all men whom we suffer let us pray, from God let us never depart. Our patrimony let Him be, our hope let Him be, our safety let Him be. He is Himself here a comforter, there a remunerator, everywhere Maker-alive, and of life the Giver, not of another life, but of that whereof has been said, “I am the Way, and the Truth, and the Life:” in order that both here in the light of faith, and there in the light of sight, as it were in the light of the living, in the sight of the Lord we may be pleasing.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)