  A distinctive feature of the presence of spontaneous chiral symmetry breaking
in QCD is the condensation of low modes of the Dirac operator near the origin.
The rate of condensation must be equal to the slope of (Mpi^2 Fpi^2)/2 with
respect to the quark mass m in the chiral limit, where Mpi and Fpi are the mass
and the decay constant of the Nambu-Goldstone bosons. We compute the spectral
density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar
meson mass and decay constant by numerical simulations of lattice QCD with two
light degenerate Wilson quarks. We use CLS lattices at three values of the
lattice spacing in the range 0.05-0.08 fm, and for several quark masses
corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this
coverage of parameters space, we can extrapolate all quantities to the chiral
and continuum limits with confidence. The results show that the low quark modes
do condense in the continuum as expected by the Banks-Casher mechanism, and the
rate of condensation agrees with the Gell-Mann-Oakes-Renner (GMOR) relation.
For the renormalisation-group-invariant ratios we obtain [\Sigma^RGI]^(1/3)/F
=2.77(2)(4) and Lambda^MSbar/F = 3.6(2), which correspond to [\Sigma^\MSbar(2
GeV)]^(1/3) =263(3)(4) MeV and F=85.8(7)(20) MeV if FK is used to set the scale
by supplementing the theory with a quenched strange quark.
