In this context, subtle bodies can be different apparent forms: ideas, descriptions, concepts, mental constructions, convictions…
Mind copies biological phenomena from the physical world and applies them in the realm of the psyche. A battle for 'existence' evolves. Being is imagined as an object that behaves as a truly existing body.
Along with identification with bodies come complementary spheres. The physical forms belong to the physical world… subtle forms dwell in subtle worlds. Through identification it seems as if a 'me' is in a space. 'Body' and 'space' are imaginations of the mind.