In Rome, there were little patio restaurants all along the streets and alleyways, with hosts and hostesses positioned outside to usher people in.
What seemed to be happening was that if a given restaurant was empty, people were less likely to sit down, so that if one person could sit down, the staff would be overjoyed. Sure enough, more people would follow and sit, reassured that there was at least one person sitting at a given restaurant.
In the same way, if one is alone or isolated, one has to work doubly hard to build up connections. For most people, a single signal is not enough to get one's attention. There has to be a current, in an electrical sense. There has to be exchange activity, there has to be a social buzz. Otherwise they won't approach.
