The discussion centers on a request for classical mechanics resources, particularly those with a focus on celestial mechanics and mathematical rigor. The original poster expresses interest in understanding Kepler orbits and seeks textbooks that provide rigorous mathematical derivations, such as why orbits around the sun are elliptical. However, a response cautions that while Abraham and Marsden's "Foundations of Mechanics" offers a highly abstract and sophisticated mathematical treatment, it may not effectively teach practical physics or problem-solving skills. The conversation also highlights the necessity of understanding Hamiltonian formalism and perturbation theories for a serious study of celestial mechanics, suggesting that many existing textbooks in this area are challenging and somewhat outdated.