Lyric discussion by AdamCain 

Cover art for Mary's Place lyrics by Bruce Springsteen

To me this is obviously Springsteen‘s interpretation of what eternity in heaven is going to be like. Biblically speaking, ‘seven’ represents completion or perfection in God’s economy (while ‘six’ is the number of man). We see examples of this repeatably (Genesis 1, Exodus 20, 2Kings 5, Psalm 12, Matthew 18, and numerous, numerous other passages. I believe that’s what Bruce is alluding to with his references to ‘seven’