  We prove the Plancherel formula for spherical Schwartz functions on a
reductive symmetric space. Our starting point is an inversion formula for
spherical smooth compactly supported functions. The latter formula was earlier
obtained from the most continuous part of the Plancherel formula by means of a
residue calculus. In the course of the present paper we also obtain new proofs
of the uniform tempered estimates for normalized Eisenstein integrals and of
the Maass-Selberg relations satisfied by the associated C-functions.
