What are the rites of passage in "By the Waters of Babylon"?
We need to remember the setting of this great story - it is centred in a post-nuclear world where humanity has been reduced to a kind of stone age civilization. Thus there is heavy emphasis on taboos and things that are "forbidden", which we would normally associate with primeval societies. It is clear that John, as the son of a priest and one who is due to follow in his father's footsteps, must go on his own "rite of passage" to become a man and a fully-fledged priest:
When I was man at last, I came to my father and said, "It is time for me to go on my journey. Give me your leave."
Thus his father purifies his son in a special rite and the son looks into the smoke of the fire and sees the destination that he must journey to - even though it is forbidden to go to the Place of the Gods. It is this that is John's challenge that he needs to achieve to become a man and a priest. As his father says:
"Once I had young dreams. If your dreams do not eat you up, you may be a great priest. If they eat you, you are still my son. Now go on your journey."
Thus he is sent and given this warning by his father before setting off on a journey that will challenge his very understanding of the world as he knows it and change his future for ever.