It is a question which I still don’t know how to answer….
I have this tendency, and I am not sure if it is because curiosity or perfectionism, that I want to include in my writing (no matter if it is a thesis or a paper) almost all literature which exists in a particular topic. I am totally crazy with “original sources” (my students from Bremen know something about that ;)), that is why I always try to go to this very old books, and papers, and read them by myself than “cite someone who cite someone”, and rely on what other people wrote about this or that work. In the end I spend hours going from one book to another, from a reference list in one article to dozens of new pdf. downloaded, and it is like a ”never-ending story”….
And I always ask myself the question – when enough is enough?