  The calculation of the mass of light scalar isosinglet meson within the
Shifman-Vainshtein-Zakharov (SVZ) sum rules is revisited. We develop simple
analytical methods for estimation of hadron masses in the SVZ approach and try
to reveal the origin of their numerical values. The calculations of hadron
parameters in the SVZ sum rules are known to be heavily based on a choice of
the perturbative threshold. This choice requires some important ad hoc
information. We show analytically that the scalar mass under consideration has
a lower and upper bound which are independent of this choice: $0.78\lesssim
m_s\lesssim1.28$ GeV.
