14 But I ask, what is that cry of the poor, which God forgets not? Is it that cry, the words whereof are these, “Pity me, O Lord, see my humiliation at the hands of my enemies”?. Why then did he not say, Pity “us” O Lord, see our humiliation at the hands of “our” enemies, as if many poor were crying; but as if one, Pity “me,” O Lord? Is it because One intercedes for the Saints, “who” first “for our sakes became poor, though He was rich;” and it is He who says, “Who exaltest me from the gates of death, that I may declare all Your praises in the gates of the daughter of Sion”?
For man is exalted in Him, not that Man only which He bears, which is the Head of the Church; but whichsoever one of us also is among the other members, and is exalted from all depraved desires; which are the gates of death, for that through them is the road to death. But the joy in the fruition is at once death itself, when one gains what he has in abandoned wilfulness coveted: for “coveting is the root of all evil:” and therefore is the gate of death, for “the widow that lives in pleasures is dead.” At which pleasures we arrive through desires as it were through the gates of death.
But all highest purposes are the gates of the daughter of Sion, through which we come to the vision of peace in the Holy Church....Or haply are the gates of death the bodily senses and eyes, which were opened when the man tasted of the forbidden tree,... and are the gates of the daughter of Sion the sacraments and beginnings of faith, which are opened to them that knock, that they may arrive at the hidden things of the Son?...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)