Mass - Energy - Momentum in General Relativity . Only there because of Spacetime ?

I describe how relativistic field theory generalises the defining property of material systems to possess mass to the requirement of them having a mass-energy-momentum density tensor Tμν (energy tensor for short) associated with them. I argue that according to general relativity Tμν is not an intrinsic property of matter, looking at how the energy tensor for a relativistic material system can be derived in a Lagrangian framework. It will become evident that the matter fields Φ alone are not sufficient for such a derivation. The metric field gμν plays a prominent role in obtaining the energy tensor of a material system, and occurs explicitly in a generic Tμν . Accordingly, since gμν represents the geometry of spacetime itself, the properties of mass, stress, energy and momentum should not be seen as intrinsic properties of matter, but as relational properties that material systems have only in virtue of their relation to spacetime structure.