  We select sum rules from which one can extract directly reliable limits on
the size of the chiral symmetry breaking light quark condensate
$<\bar\psi\psi>$. Combined results from the nucleon and $B^*-B$ mass-splitting
sum rules give a result compatible with the standard value: $<\bar\psi\psi> (1
GeV) \simeq (-229 MeV)^3$, through the determinations of the quark-gluon mixed
condensate. The vector form factor of the $D\rar K^*l\nu$ semi-leptonic decay
leads to the range $0.6\leq <\bar\psi\psi> (-229 MeV)^3 \leq 1.5$. The upper
limit combined with the Gell-Mann-Oakes-Renner (GMOR) relation implies the
interesting lower bound on the sum of light quark masses:$(m_u+m_d) (1 GeV)
\geq$ 9.4 MeV, which combined with the ratio of light quark masses from chiral
perturbation theory leads to $m_s (1 GeV) \geq (121\pm 12)$ MeV. The lower
limit combined with the positivity of the $m_q^2$ contribution to the GMOR
relation leads to the upper bound : $(m_u+m_d) (1 GeV) \leq$ 15.7 MeV, which is
independent on the nature of chiral symmetry breaking.
