The ambitious aim of a holistic unified theory is achieved by a consequent utilization of the principle of causality. In doing so, the first step is to remove the electron from Maxwell's theory, to be finally derived as a calculable structure of a potential vortex.  The field-theoretical approach replaces the former electric source field free of vortices, by a vortex field free of quanta, that is, by the field of the potential vortices. This proves to be the result of a strict mathematical derivation, which does without the need for postulates or neglects. The approach consists of two equations of transformation (given on the envelope).  As a consequence, well-known paradoxes of the theory of relativity are solved, if a measure of length dependent on the field constitutes the base of the theory of objectivity, if thus gravitation, temperature and all known interactions, explained by a single physical phenomenon, back up the holistic theory of everything.