The analysis of the asymptotic behavior of Ornstein - Zernike equation shows that the phase transitions on binodal cannot exist in the standard theory, which accounts for the analytical solutions only. To obtain the transitions it is necessary to build the nonlinear theory. The elements of nonlinearity can be introduced into the statistical mechanics by means of the infinite point of the pair correlation function. It allows one to describe the critical phenomena in complete agreement with the experimental data and with the scaling theory, as well as to explain the nature of the liquid - vapor phase transitions. In addition, the developed theory explains a number of effects in a regular area of phase diagram. So the infinite point influences on the state of liquids not only in the critical point vicinity but also at entire phase diagram.