This paper is an exploration of the concept of energy, illuminated by the transformative insights of
the special theory of relativity. Focusing on potential energy ( PE ), it will be shown that PE as
presently defined is in conflict with the tenets of special relativity. Even though PE remains an
indispensable theoretical device its actual physicality is questionable. Moreover its ontological
status is quite different from that of both kinetic energy and mass, a significant point that is not
widely appreciated. We will establish that PE is a theoretical concept as opposed to an empirical
one; it is a descriptor of mass–energy without a detectable physical presence of its own. PE is a
measure of energy stored, it is not the energy stored.