This song feels very pessimistic and very true to me. At 5 years old (or thereabouts) you realise you're not invulnerable, and from there on it's all loss, decay and death. But in your dreams you remember the fantasy of invulnerability you used to have: you dream of flying. Then you wake up crying because the fantasy is so beautiful it touches you, and also because you realise it's unattainable in real life, so yopu feel the sense of disillusionment and loss you felt at five years of age all over again.
This song feels very pessimistic and very true to me. At 5 years old (or thereabouts) you realise you're not invulnerable, and from there on it's all loss, decay and death. But in your dreams you remember the fantasy of invulnerability you used to have: you dream of flying. Then you wake up crying because the fantasy is so beautiful it touches you, and also because you realise it's unattainable in real life, so yopu feel the sense of disillusionment and loss you felt at five years of age all over again.