  We show how the scalar field, a candidate of quintessence, in a proposed
model of the scalar-tensor theories of gravity provides a way to understand a
small but nonzero cosmological constant as indicated by recent observations. A
particular emphasis is placed on the effort to inherit the success of the
scenario of a decaying cosmological constant. Discussions of a possible link to
non-Newtonian gravity, the coincidence problem, the issue of time-variability
of coupling constants as well as the chaos-like nature of the solution are also
included in a new perspective.
