It seems to me to be true that heavens are placed in the sky because it is the unreachable. The unreachable and therefore the unknowable always seems divine--hence, religion. People need religion because the great masses fear life and its consequences. Its responsibilities weigh heavy. Feeling a weakness in the face of great forces, men seek an alliance with omnipotence to bolster up their feeling of weakness, even though the omnipotence they rely upon is a creature of their own minds. It gives them a feeling of security.
