  Despite the importance of the variational principles of physics, there have
been relatively few attempts to consider them for a realistic framework. In
addition to the old teleological question, this paper continues the recent
discussion regarding the modal involvement of the principle of least action and
its relations with the Humean view of the laws of nature. The reality of
possible paths in the principle of least action is examined from the
perspectives of the contemporary metaphysics of modality and Leibniz's concept
of essences or possibles striving for existence. I elaborate a modal
interpretation of the principle of least action that replaces a classical
representation of a system's motion along a single history in the actual
modality by simultaneous motions along an infinite set of all possible
histories in the possible modality. This model is based on an intuition that
deep ontological connections exist between the possible paths in the principle
of least action and possible quantum histories in the Feynman path integral. I
interpret the action as a physical measure of the essence of every possible
history. Therefore only one actual history has the highest degree of the
essence and minimal action. To address the issue of necessity, I assume that
the principle of least action has a general physical necessity and lies between
the laws of motion with a limited physical necessity and certain laws with a
metaphysical necessity.
