  In this paper, I consider the issue of how two mathematical models of modern
physics, the variational principles and the quantum path integral formalism,
relate to reality. I assume that the observed phenomena are consistent with the
calculations because both of these models have some common ontological
foundations. According to the hypothesis of the summation of coexisting
alternative possibilities, at the quantum level, the system at once moves along
all histories that possible in given boundary conditions. The actual history is
a mere result of the summation of all these alternative possible histories.
This resultant history differs from others with the minimal action and maximal
probability. I observe this history as a macroscopic trajectory of the system.
