Even then the astral corpse still remains, but when it is quite without any trace of its former life we call it a "shell".

Of itself a shell cannot communicate at a seance, or take any action of any sort; but such shells are frequently seized upon by sportive nature-spirits and used as temporary habitations.

A shell so occupied _can_ communicate at a seance and masquerade as its original owner, since some of his characteristics and certain portions of his memory can be evoked by the nature-spirit from his astral corpse.
When a man falls asleep, he withdraws in his astral body, leaving the whole of the physical vehicle behind him.

When he dies, he draws out with him the etheric part of the physical body, and consequently has usually at least a moment of unconsciousness while he is freeing himself from it.

The etheric double is not a vehicle and cannot be used as such; so when the man is surrounded by it, he is for the moment able to function neither in the physical world nor the astral.