Have I got this right?
At the dawn of our cosmos, only 'pure energy' is believed to have existed. No particles, not even photons. That energy transformed itself into all that exists today, owing to a bundle of fundamental laws that came with the package.
Something is known about the ways energy now manifests itself, and how it can be described in different ways as it's transferred from one form to another, all the while being conserved (well, so long as it doesn't disappear into another universe, I guess it would have to be). But almost all of the energy in the cosmos seems to be in forms that were entirely unsuspected until very recently, i.e. the mysterious Dark Matter and Dark Energy. Yet, even if/when those mysteries are solved, we will still not know what energy is in terms of anything else. As Bill Gill said, energy is energy.
