Mr. Spencer is Holden's history teacher. Holden has managed to flunk every single one of Mr. Spencer's classes. Interestingly enough, Holden says that Mr. Spencer is his favorite teacher. Holden is on his way to see Mr. Spencer because Mr. Spencer left Holden a note that asked him to come by his house. Mr. Spencer wants to say goodbye to Holden and give him some advice as well.
The entire scene is a real downer, because it's obvious that Holden initially respects Mr. Spencer and that Mr. Spencer cares for Holden. Unfortunately, Holden is put off by how Mr. Spencer is dressed and takes offense to Mr. Spencer's advice about Holden needing to think about his future.
What made it even more depressing, old Spencer had on this very sad, ratty old bathrobe that he was probably born in or something. I don't much like to see old guys in their pajamas and bathrobes anyway. Their bumpy old chests are always showing. And their legs. Old guys' legs, at beaches and places, always look so white and
The scene takes place in chapter one and two and doesn't do a lot to ingratiate Holden to the reader. But as a person reads the book, he/she realizes that the opening scene is par for the course concerning Holden and his attitude.