Quote

"The best thing though, in that museum was that everything always stayed right where it was. Nobody'd moved. You could go there a hounded thousand times, and that Eskimo would still be just finished catching those those two fish, the birds would still be on their way south, the deers would still be drinking out of that water hole, with their pretty antlers and their pretty skinny legs, and that squaw with the naked bosom would still be weaving that same basket. Nobody'd be different. The only thing that would be different would be you."

This quote is Holden talking about the museum and how it has always been a constant in his life, how it never changes even as everything else does.

I think that Holden loves the museum so much because it's one of the very few things in his life that seems constant. Everything else changes; his brother dies, he gets kicked out of schools, his brother goes off to Hollywood. I think Holden is striving to find something that will always be there, and the most reliable thing he's found so far is the museum. I think that Jane is another constant in his life, and I think that one of the reasons he hasn't called her yet is that he's afraid that things will have changed between them.