What does it mean in this song?
What does it mean when “phantom doors swing”?
What is your premise about the “all natural things” you saw around you?
What is a phantom something that is not really present. Is it visible in ghostly and/or spectral ways?
When we speak of phantom limbs it is the sensation an amputee gets that is still present even after removing the limb from the frame.
Usually a new door/door is a ghostly door, but much of its intent is to be a phantom door. With no formal interpretation we don’t engage in literary interpretation.