Gossip, Shoptalk, and Small Talk : Page 257
Among people of the same shop, some of the more progressive members will urge that they all get away from the "shop" now and then. This is right. However, the good conversationalist, rather than explicitly calling for a change of topic, will so try to raise the level from personalities to broader problems that the smell of the shop will practically be lost. In short, the only important rule about shoptalk is not to indulge in it when anyone is not of the shop.
When people of different shops, of different trades and professions, meet, they should at first properly indulge in what is called small talk. It is a sort of sparring for each other's interests. It is talk which flits back and forth on harmlessly personal or insignificantly impersonal topics. When three strangers are introduced and sit at the same table, they will talk a bit about the dining room, the city, the transportation system, the food, until by degrees, coming to know each other well enough, they will rise to more significant topics like the income tax, socialized medicine, and existentialism. Until they reach this level, they are indulging in small talk. It is an important art.