Feynman notices Princeton graduate students tend to socialize among members of their own departments (physicists eat with other physicists, for example). He decides he wants to see what people outside his department are doing, and begins to eat in the dining hall with people from other departments.
The philosophy students he eats with invite him to a seminar. At the seminar they get into a discussion where they are trying to define an "essential object," which leads to related series of arguments about the nature of a brick. At the end of the seminar, Feynman still is not sure what an "essential object" is, but is fascinated at the number of ways people have found to look at a brick.
When he has dinner with the biology.....
