  We show that perturbation theory provides two distinct mechanisms for the
power like growth of hadronic cross sections at high energy. One, the leading
BFKL effect is due to the growth of the parton density, and is characterized by
the leading BFKL exponent. The other mechanism is due to the infrared
diffusion, or the long range nature of the Coulomb field of perturbatively
massless gluons. When perturbative saturation effects are taken into account,
the first mechanism is rendered ineffective but the second one persists. We
suggest that these two distinct mechanisms are responsible for the appearance
of two pomerons. The density growth effects are responsible for the hard
pomeron and manifest themselves in small systems (e.g. gamma^* or small size
fluctuations in the proton wave function) where saturation effects are not
important. The soft pomeron is the manifestation of the exponential growth of
the black saturated regions which appear in typical hadronic systems. We point
out that the nonlinear generalization of the BFKL equation which takes into
account wave function saturation effects ("pomeron loops") provides a well
defined perturbative framework for the calculation of the soft pomeron
intercept. The conjecture of a perturbative soft pomeron is consistent with
picturing the proton as a loosely bound system of several small black regions
corresponding e.g. to constituent quarks of size about 0.3 fm. Phenomenological
implications of this picture are compatible with the main qualitative features
of data on p-p scattering.
