  We apply Bogolubov approach to QCD with two light quarks to demonstrate a
spontaneous generation of an effective interaction, leading to the Nambu --
Jona-Lasinio model. The resulting theory contains two parameters: average
low-energy value of $\alpha_s$ and current light quark mass $m_0$. All other
low-energy parameters: the pion decay constant, mass of the $\pi$-meson, mass
of the $\sigma$-meson and its width, the constituent quark mass, the quark
condensate are expressed in terms of the two input parameters in satisfactory
correspondence to experimental data and chiral phenomenology. {\it E.g.} in the
approximation being used we have for $\alpha_s = 0.67$ and $m_0 = 20 MeV$:
$f_\pi = 93 MeV, m_\pi = 135 MeV, m_\sigma = 492 MeV, \Gamma_\sigma = 574 MeV,
m_q = 295 MeV, <\bar q q> = -(222 MeV)^3$.
