1 The Church speaks to Christ: “The Lord feeds me, and I shall lack nothing”. The Lord Jesus Christ is my Shepherd, “and I shall lack nothing.”
2. “In a place of pasture there has He placed me”. In a place of fresh pasture, leading me to faith, there has He placed me to be nourished. “By the water of refreshing has He brought me up.” By the water of baptism, whereby they are refreshed who have lost health and strength, has He brought me up.
3. “He has converted my soul: He has led me forth in the paths of righteousness, for His Name's sake”. He has brought me forth in the narrow ways, wherein few walk, of His righteousness; not for my merit's sake, but for His Name's sake.
4. “Yea, though I walk in the midst of the shadow of death”. Yea, though I walk in the midst of this life, which is the shadow of death. “I will fear no evil, for You are with me.” I will fear no evil, for You dwell in my heart by faith: and You are now with me, that after the shadow of death I too may be with You. “Your rod and Your staff, they have comforted me.” Your discipline, like a rod for a flock of sheep, and like a staff for children of some size, and growing out of the natural into spiritual life, they have not been grievous to me; rather have they comforted me: because You are mindful of me.
5. “You have prepared a table in my sight, against them that trouble me”. Now after the rod, whereby, while a little one, and living the natural life, I was brought up among the flock in the pastures; after that rod, I say, when I began to be under the staff, You have prepared a table in my sight, that I should no more be fed as a babe with milk, but being older should take meat, strengthened against them that trouble me. “You have fattened my head with oil.” You have gladdened my mind with spiritual joy. “And Your inebriating cup, how excellent is it!” And Your cup yielding forgetfulness of former vain delights, how excellent is it!
6. “And Your mercy shall follow me all the days of my life:” that is, as long as I live in this mortal life, not Yours, but mine. “That I may dwell in the house of the Lord for length of days”. Now Your mercy shall follow me not here only, but also that I may dwell in the house of the Lord for ever.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)