It is indeed a very geometrical picture since position is just as much of a state as spin is. Position just has a few huge dimensions as its degrees of freedom. We don't know _yet_ whether position is continuously valued or discrete.

Gravity being quantum would most likely indicate that position is also discrete.

Since all energy, being allocated for external movement or just internal time, produces the same amount of gravity, it appears that the act of any state change induces gravity. Einstein never really gave a physically understandable reason for why all change causes gravitation, but it's likely similar to a ship in water. If the ship is rocking really fast, the waves that emanate from it can pull objects towards it. The rocking is just state change and even for a rest mass, we know that it's a loop of energy, there really is no static storage of mass.. it's a process of energy containment and cyclic change.