The discussion centers on the relationship between stress, force, and area in a solid body under equilibrium. It emphasizes that internal stresses must sum to zero to maintain equilibrium; otherwise, the body would fail. The integral of the pressure difference (Delta P) must equal the sum of the pressures at the surfaces removed (P1 and P2) when bisecting the body. The participants clarify that calculating stress as force divided by area is essential, and integrating stress over the area can yield the resultant force. Overall, understanding these principles is crucial for analyzing solid bodies in equilibrium.