It is written that the 7 shepherds come to visit us in the Sukkah, each one leading the group of shephards into the Sukkah, night after night, for the seven nights of Sukkot.
The 7 shephards:
how does that work? Their souls travel through the Sukkah, like a portal between worlds.
The waving of the Lulav & Etrog is like the key that opens the door to the other side.