  The prediction of a massless boson after the spontaneous chiral symmetry
breaking in the classic paper of Nambu and Jona-Lasinio (NJL) is shown to be
wrong. Their mistake is due to a carelessly employed perturbative vacuum when
evaluating the boson mass by summing up one loop Feynman diagrams. With the
proper symmetry broken vacuum, one obtains a finite boson mass depending on the
coupling constant $G$.
