  Generalizing the Bogoliubov model of a weakly non-ideal Bose gas to massless
$\lambda\varphi^4$ theory we show that spontaneous breaking of symmetry occurs
due to condensation in a coherent vacuum % which is energetically favoured
compared to the perturbative one. and leads to a vacuum energy density which is
lower than that obtained by Coleman and Weinberg using the one-loop effective
potential method. We discuss the alternative of a squeezed condensate and find
that for the massless $\lambda \varphi^4$ theory spontaneous symmetry breaking
to a squeezed vacuum does not occur.
