It seems to be a common idea that your heart is locked up and needs to be set free. I’m not sure where the idea came from personally but I do listen to lots of songs and I’m sure that this imagery is in some of them. Certainly my girl is … hmm she is only playing with the cage.. she could be locking it up.. or setting it free. I must admit to feeling she is setting it free but I guess like all art it is open to interpretation. Your choice!