The discussion revolves around calculating the volume of a secret cavity in a brass sculpture, given its weight in air and water. The weight difference when submerged indicates a buoyant force of 1.9 N, which can be used to determine the volume of the cavity using Archimedes' principle. The density of brass is noted as 8470 kg/m³, and the assumption is made that the cavity likely contains air. The conversation highlights the importance of understanding the contents of the cavity to accurately solve the problem. Ultimately, the calculation hinges on the relationship between buoyancy and volume displacement.