  We show that large leptonic mixing occurs most naturally in the framework of
the Sandard Model just by adding a fourth generation. One can then construct a
small $Z_4$ discrete symmetry, instead of the large $S_{4L}\times S_{4R}$,
which requires that the neutrino as well as the charged lepton mass matrices be
proportional to a $4\times 4$ democratic mass matrix, where all entries are
equal to unity. Without considering the see-saw mechanism, or other more
elaborate extensions of the SM, and contrary to the case with only 3
generations, large leptonic mixing is obtained when the symmetry is broken.
