A pub is...

…"the only kind of public building used by large numbers of ordinary people where their thoughts and actions are not being in some way arranged for them; in the other kinds of public building they are the audiences, watchers of political, religious, dramatic, cinematic, instructional or athletic spectacles. But within the four walls of the pub, once a man has bought or been bought his glass of beer, he has entered an environment in which he is a participator rather than a spectator."