The discussion centers on the financial aspects of textbook publishing, particularly in physics and mathematics. Popular textbooks, such as Griffiths' Electrodynamics and Quantum Mechanics, are noted for their high prices, leading to speculation about the authors' earnings. It's suggested that textbook authors typically earn royalties ranging from 2% to 20% of the book price, with best-selling authors potentially making around $100,000 annually. The conversation highlights that introductory texts generate more revenue due to higher sales volumes, while graduate texts sell less and yield lower royalties. Notably, James Stewart, author of a widely used calculus textbook, reportedly amassed significant wealth from his publications, with his home, Integral House, symbolizing his financial success. The discussion also emphasizes the challenges of breaking into the textbook market and the constant demand for new editions. Overall, the financial dynamics of textbook publishing reveal a lucrative but competitive landscape for authors, particularly in subjects with high student enrollment.