A gateway, an opening, a portal from one understanding to another. A clue to the meaning is found in the meditation
"I am, by thinly veiled design, the threshold to other dimensions. In my ending is my beginning. The initatory gateway awaits."
This is the seventh or last archetype in the cycle of development of primary beings. It represents the power found in completion. Seen as a closure, which is really an opening to another level of being.