  We describe an action principle, within the framework of the Eddington
gravity, which incorporates the matter fields in a simple manner.
Interestingly, the gravitational field equations derived from this action is
identical to the Einstein's equations, in contrast with the earlier attempts in
the literature. The cosmological constant arises as an integration constant in
this approach. In fact, the derivation of the field equations demands the
existence of a non-zero cosmological constant, thereby providing the raison
d'\^{e}tre for a non-zero cosmological constant, implied by the current
observations. Several features of our approach strongly support the paradigm
that gravity is an emergent phenomenon and, in this perspective, our action
principle could have a possible origin in the microstructure of the spacetime.
We also discuss several extensions of the action principle, including the one
which can incorporate torsion in the spacetime. We also show that an
Eddington-like action can be constructed to obtain the field equations of the
Lanczos-Lovelock gravity.
