  In this essay, we wish to propose a general principle: \it{the equation of
motion or dynamics of a fundamental force should not be prescribed but instead
be entirely driven by geometry of the appropriate spacetime manifold, and the
equation is then obtained by employing only the geometric property without
appeal to an action.} The motivation for this pronouncement comes from the fact
that the equation of motion of general relativity follows from the geometry of
Riemannian spacetime manifold without appeal to anything else from outside. The
driving differential geometric property is the Bianchi identity satisfied by
the Riemann curvature tensor. Similarly it is geometry of the principal tangent
bundle of fibre spacetime manifold that may account for dynamics of the gauge
vector fields. It is the classical electric force for the Abelian gauge
symmetry group while the non-Abelian symmetry leads to the non-Abelian forces,
the weak and the strong. We shall also reflect on a unified picture of the
basic forces, and the duality correspondences it may inspire.
