  We discuss the limitations of the applicability of the Lifshitz formula to
describe the temperature dependence of the Casimir force between two bulk lossy
metals. These limitations follow from the finite sizes of the interacting
bodies. Namely, Lifshitz's theory is not applicable when the characteristic
wavelengths of the fluctuating fields, responsible for the
temperature-dependent terms in the Casimir force, is longer than the sizes of
the samples. As a result of this, the widely discussed linearly decreasing
temperature dependence of the Casimir force can be observed only for dirty
and/or large metal samples at high enough temperatures. This solves the problem
of the inconsistency between the Nernst theorem and the "linearly decreasing
temperature dependence" of the Casimir free energy, because this linear
dependence is not valid when $T \to 0$
