  The equations of motion describing all physical systems, except gravity,
remain invariant if a constant is added to the Lagrangian. In the conventional
approach, gravitational theories break this symmetry exhibited by all other
physical systems. Restoring this symmetry to gravity and demanding that
gravitational field equations should also remain invariant under the addition
of a constant to a Lagrangian, leads to the interpretation of gravity as the
thermodynamic limit of the kinetic theory of atoms of space. This approach
selects, in a very natural fashion, Einstein's general relativity in $d=4$.
Developing this paradigm at a deeper level, one can obtain the distribution
function for the atoms of space and connect it up with the thermodynamic
description of spacetime. This extension relies on a curious fact that the
quantum spacetime endows each event with a finite area but zero volume. This
approach allows us determine the numerical value of the cosmological constant
and suggests a new perspective on cosmology.
