Northern had sort of an idea of it before entering the academy; after entering the academy and burying his brain in books, that idea had escalated into a small room of knowledge.
He could say with surety that as every soul generated from a certain constellation, and there were twelve constellations in total, which further progressed to become the twelve markings of time flow sequence of Ul'Tra-el into twelve months, each month named after the constellations.
Because it was blasphemy for their names to be uttered by mortal mouth. For beings without active consciousness, Northern could not understand what the deal was with that particular rule; it was not as if they would strike one down with thunder.
They can't, because they are not actively conscious. The constellations operated on passive consciousness—one could consider them more or less trees.
