The discussion centers around the calculus textbook "Calculus and Analytic Geometry" by George B. Thomas and Ross L. Finney, highlighting its historical significance and evolution over the years. Participants reminisce about their experiences with the book, noting its use in various college courses since the 1980s and the perceived decline in quality of later editions after the authors' deaths. There is speculation about the original poster's intent in mentioning the book, with some suggesting it might be an attempt to sell it. The conversation also touches on the existence of multiple editions and variations of the Thomas and Finney text, including those adapted for high school AP courses. Additionally, there is a discussion about the rigor of the Finney book compared to other calculus texts, like Apostol, with a request for recommendations on which book to use for epsilon-delta proofs.