  We consider a possibility that the cosmological constant may not be a
constant, but a free thermodynamical variable. To this end we construct a
microscopic model of a spacelike two-sphere just inside of the cosmological
horizon of the de Sitter spacetime. In our model the spacelike two-sphere in
question is assumed to consist of discrete constituents, each of them
contributing to the two-sphere an area, which is in an integer times a
constant. Using our model we obtain a thermodynamical equation of state for the
cosmological constant. Our equation of state implies that the cosmological
constant has a certain positive lower bound, which depends on the number of the
constituents of the two-sphere.
