Scalar-tensor theories provide the simplest
model-independent description of unification theories, e.g. strings,
which forecast couplings between scalars and curvature.
In this work we investigate the conditions under which general
scalar-tensor gravity theories relax towards General Relativity.
We extend the work of Damour and Nordtvedt (Phys. Rev. D {\bf 48},
3436 (1993)) by studying the effects of the inclusion of a cosmological
potential term. When the universe is both radiation
dominated or vacuum, we find that Einstein's gravity is
indeed a cosmological attractor provided that the universe exhibits
inflationary expansion. This latter feature provides another striking
argument in favour of the inflationary paradigm, and we show that it
arises without intervention of the usual inflaton field.