Behind the physical world of matter (atoms, protons, electrons), and the subtle astral world of luminous life energy (lifetrons), is the causal, or ideational, world of thought (thoughtrons). After man evolves sufficiently to transcend the physical and astral universes, he resides in the causal universe. In the consciousness of causal beings, the physical and astral universes are resolved to their thought essence. Whatever physical man can do in imagination, causal man can do in actuality—the only limitation being thought itself. Ultimately, man sheds the last soul covering—his causal body —to unite with omnipresent Spirit, beyond all vibratory realms.