A thought experiment ... You have a mass sitting in space far from any source of gravity. We know the energy it contains from e = inertial mass x speed of light squared. Using a different approach, what would you have to sum to get this total energy from properties of the mass such as 1. Total binding energy or all chemical bonds. 2. Total binding energy of nuclear forces. etc? Is this an approach that would ever sum to inertial mass x speed of light squared?