Full Idea
A closer examination of the concepts and principles of relativity shows that they rest squarely on an ontology of things and events (not on convenient 'space-time diagrams'). Acceleration concerns non-zero mass, but only continuants can have a mass.
Gist of Idea
Relativity has an ontology of things and events, not on space-time diagrams
Source
Peter Simons (Parts [1987], 3.4)
Book Reference
Simons,Peter: 'Parts: a Study in Ontology' [OUP 1987], p.127
A Reaction
The point here is that fans of four-dimensionalism like to claim that they are more in touch with modern physics, because 'time is just another dimension, like space, so objects are spread across it'. Simons sounds right about this.