Billy Joel - Vienna Lyrics Meaning

I think this song refers to both specific names and quotes that symbolize the moral of the song, but I believe the main idea is this: Billy Joel is writing about how as a kid, either he in the past, or someone who inspired him, is struggling to believe that his integrity in chasing his dream is there. He questions himself all too often, and is frantic to prove to himself that he lives up to what he wants out of himself. He has outstanding ambition and character and surely understands, as a teenager, the cold reality of how choices and dedication impact one's turnout in life and who they become ("You know that when the truth is told, that you can get what you want or you can just get old."), but he personalizes this very much and can't relax. Sometimes, his ambition leaves him a scattered mess and causes him to overshoot the simple defaults in his life as he is so overwhelmingly focused on his goals ("You're so ahead of yourself that you forgot what you need"), and his drive and focus, which is a blessing, is actually something that is causing anxiety to him at the same time. The song seems to be Billy Joel talking to his young self, as he has gained wisdom through age, telling him to keep that ambition and drive, but to stay level-headed and be patient with it. This will allow him to enjoy life before he floods it all with worry, while still keeping focus, and be more efficient so that he's not a mess and doesn't miss the basic important things that are right under his nose.