Augustine. Exposition on the Book of Psalms. Schaff, Philip (editor). New York: Christian Literature Publishing Co, 1886. Nicene and Post-Nicene Church Fathers: Series 1: Volume VIII. Re-published 2014, Catholic Way Publishing. Kindle electronic edition, ISBN-13: 978-1-78379-372-3.
Augustine observes that the content of Psalm 87 is very deep, as it shows how God in Christ has made a way throughour world of trials to reach our city of eternal blessedness (Augustine Psalms, loc. 333772, par. 1). The foundations of this city are established on "holy =hills," which would be identified as the Prophets and the Apostles (Augustine Psalms, loc. 333785, par. 2). Augustine goes on to tie this city of God to the new heavenly Jerusalem, built on the foundation of Jesus himself. He then proceeds to speak of numerous figures used in Scripture to represent Christ - a foundation, pillar, door, shepherd, etc. If Christ is the foundation, then the building is one of living stones, Christ's people, built by Him (Augustine Psalms, loc. 333819, par. 3). Augustine then asks what the city is like.
In verse two the focus shifts to the gates of the city. Augustine is clear that he considers the gates and the foundations both to represent Christ. However, they have functional differences. We enter God's city through the gate (Augustine Psalms, loc. 333825, par. 4). It is significant to Augustine that we find portrayals of one gate and of twelve gates. The twelve symbolize not only the twelve apostles, but also the four cardinal directions, thus the whole world. No matter where you come from, each side has a threefold gate, symbolic of the Trinity (Augustine Psalms, loc. 333839, par. 4). Verses 3-4 speak of the excellency of God's city, but also the consideration of "Rahab and Babylon." Augustine notes that Rahab was protected by God though she was not of Israel (Augustine Psalms, loc. 333852, par. 5). Jesus is the one who is able to save people from every nation. Augustine addresses this as a "deep mystery" because God is in the process of turning Babylon into Jerusalem (Augustine Psalms, loc. 333859, par. 6).
God gives assurance to His people when, in verse six, God reviews His mercy fo His people to know they belong to His city (Augustine Psalms, loc. 333878, par. 7). No matter the social rank of the person, God makes him into a prince, giving him glory. Verse seven describes the result as being given a dwelling full o joy (Augustine Psalms, loc. 333885, par. 8). Here Augustine finds a place with no sorrow at all. He even asks what we might do to occupy ourselves. It is a place of quiet and rest, with contentment (Augustine Psalms, loc. 333898, par. 8). Augustine does observe that our earthly delights are treated by us differently at different times and we have mixed motives about what we do. However, in the heavenly rest we will no longe have the mixed motives. The joy and blessing will be genuine.