A group of strangers would gather in a room. Two or three of them would be entrepreneurs or other professionals with a problem. To get into the room, they had to apply for the chance to present their problem to the others. The others were people from varied fields who had applied to volunteer their time to solve someone’s problem. A moderator would

That is protecting your guests: anticipating and intercepting people’s tendencies when they’re not considering the betterment of the whole of the group or the experience.

The host can also set the context for the gathering. When I was invited to the sixteenth annual #Agrapalooza, continuing a summer tradition of made-up games and a drunken talent show at some friends’ parents’ house, building on the rituals and memories of all the gatherings before, I was being invited into a world, not just to an event.

If everyone is invited, no one is invited—in the sense of being truly held by the group. By closing the door, you create the room.