I see a lot of sermons and blogs from friends and acquaintances who do pretty much the same thing I do, which is make comment on the day's Gospel reading for Mass (most are using John 5.1-9, which can be found here). Just to be stubborn and contrary (two skills I'm GREAT at), I decided to focus on the Epistle reading (Rev. 21.10, 21.22-22.5).
We had a long Bible study at my home parish on the Book of Isaiah and this section of Revelation reads like Isaiah, and in fact draws from it (compare Is. 25.8, 35.10, 55.1, 65.17, 66.22) and a noted passage in Ezekiel as well (Ez. 47.12). In all these visions, we see a restored, rehabilitated, and healed humanity. The old corruption, the stain of sin, the heavy weight of death is no more, and there is the image of a river which feeds trees whose fruit and leaves provide sustenance and healing. Isaiah talks about the waters of life. Revelation states the river flows from the Throne, in Ezekiel it flows from his vision of the Temple, but the images point to the actuality that this "river" flows from God Himself.
Many of us are familiar with the image of the Holy Spirit as wind, but there are many Scriptural references to the Holy Spirit as a river. Jesus specifically makes this connection in a passage in John's Gospel (Jn. 7.37-39), where He calls the Spirit in the believer's heart "living water". "Living" water means water that moves, that has a direction, that is not stagnant, and so is the Spirit.
So here we have several visions of the Spirit emanating from God. The Spirit has direction, The Spirit continuously moves. Most importantly, the Spirit heals. This is the promise won for us in Jesus' Resurrection, seen for us by the Prophets, and promised to us by Our Lord himself. There is healing out there, and it will be the Spirit of God Who will bring it to us.
Come, Holy Spirit.