In a white-water raft, everybody on board contributes to the goal of getting the boat safely down the river: the paddlers on the side, the vigilant scouts in the front, and the guide steering in the back. Everyone's effort comes together for the common purpose.
So it is in a sangha. Everyone, from the seasoned abbot on down to the newcomer just in off the street, are all contributing to the common purpose of getting the great vehicle to the other shore. No one is just along for the ride - all have a role. For example, newcomers are there if for no other reason than to provide a role for the attendants who give first-time meditation instruction. The tenzo (cook) has an important role, as does the ino, the doshi, the doan, and so on down the line, not to mention the practioners sitting on the cushions.
Today, I fulfilled my role in the Chattanooga sangha by driving up from Atlanta and sharing in their practice. Today, the Chattanooga sangha provided me the opportunity to drive up from Atlanta to share my practice. Today, my practice provided an opportunity to fulfill a role, and today, my role provided an opportunity for sangha practice in Chattanooga.
We're all in this together, and no one is superfluous.