  A systematic method of analysing Bethe-Salpeter equation using spectral
representation for the relativistic bound state wave function is given. This
has been explicitly applied in the context of perturbative QCD with string
tension in the $1 \over N$ expansion. We show that there are only a few stable
bound state mesons due to the small "threshold mass"(constituent mass) of
quarks. The asymptotic properties of the bound states are analytically
analysed. The spectrum is derived analytically and compared phenomenologically.
Chiral symmetry breaking and PCAC results are demonstrated. We make a simple
minded observation to determine the size of the bound states as a function of
the energy of the boundstate.
