Religion.

The conduct of external life is conditioned by environment, but it receives
its final quality, on which its worth depends, from the internal life which
is the self-realization of existence. Religion is the art and the theory of
the internal life of man, so far as it depends on the man himself and on
what is permanent in the nature of things.... Religion is what the
individual does with his own solitariness. It runs through three stages, if
it evolves to its final satisfaction. It is the transition from God the
void to God the enemy, and from God the enemy to God the companion. Thus
religion is solitariness; and if you are never solitary, you are never
religious.-Jonathan Edwards