I love this beautiful song also, in particular the version off the Live from Mountain Stage (1970) album. I think the song has something to do with a crisis in faith as to whether creative insides can be let out––as if the creative part wants to sing and soar but is held close to the heart. Because ... what? It might get lost, not return, if given expression. The gift he "dare not claim" but would be a feeling of grace (a gift we can't claim), which feeling would allow a release and opening outward. (This is kind of highfalutin' and absolutely not spun from any religious angle, but that's how the song strikes me.)