The discussion centers around the effectiveness of various calculus textbooks, particularly James Stewart's, in providing a solid foundation in calculus. Concerns are raised about the perceived dilution of calculus content over the years, with some participants suggesting that essential concepts are now often taught in Real Analysis courses instead of in standard Calculus I-III. While Stewart's textbook is deemed adequate for engineering and applied mathematics, some participants advocate for more rigorous texts like Apostol or Spivak for a deeper understanding, especially for those pursuing advanced studies in mathematics or engineering. The conversation highlights the balance between practical application and theoretical rigor, noting that Stewart's approach is more focused on mechanics and techniques, which may be beneficial for science majors. Overall, the consensus suggests that while Stewart's book is sufficient for many, exploring additional resources can enhance comprehension and mastery of calculus.