The astral perisprit is contained and confined within the physical body as ether in a bottle, or magnetism in magnetized iron. It is a centre and engine of force, fed from the universal supply of force, and moved by the same general laws which pervade all nature and produce all cosmical phenomena.Its inherent activity causes the incessant physical operations of the animal organism and ultimately results in the destruction of the latter by overuse and its own escape. It is the prisoner, not the voluntary tenant, of the body.
Helena Petrovna Blavatsky