You are willing to read books like this one! “The LCSH Century: One Hundred Years with the Library of Congress Subject Headings System.” [This is a link to a free download of the book. Librarians are founding members of the “sharing economy.” We educate, inform, and entertain.]
Or, support your local book-buying economy and get a bound copy suitable for gift-giving:
Stone, Alva T, ed. “The LCSH Century: One Hundred Years with the Library of Congress Subject Headings System.” New York: Routledge, 2013. 025.49 LCSH ISBN 978-0789011695
“The LCSH Century traces the 100-year history of the Library of Congress Subject Headings, from its beginning with the implementation of a dictionary catalog in 1898 to the present day. You will explore the most significant changes in LCSH policies and practices, including a summary of other contributions celebrating the centennial of the world’s most popular library subject heading language.”