First source:

This concerns you as an individual and relates to your inner world. Look carefully into your life and inner aspect, and you will discern the existence of an eternal spirit. Every person changes his or her body annually through a complete renewal, but the spirit remains unchanged.

The body is ephemeral; the spirit inhabiting it is permanent. The formation or deformation of your body's molecules, or its composition and decomposition, does not affect the spirit, which annually changes or renews its bodily garment. When it strips off this garment at the time of death, neither its permanence nor its essential nature are affected because, as established through experiences and observation, the spirit does not depend upon the body for its life. The body is only its dwelling place, not its cover. The spirit has a subtle cover, its "energetic envelope," and leaves its dwelling place dressed in this cover when its body dies.