  In this paper we reformulate free field theory models defined on the
rectangular $D+1$ dimensional lattices as $D+1$ evolution models. This
evolution is in part a simple linear evolution on free (``creation'' and
``annihilation'') operators. Formal eigenvectors of this linear evolution can
be directly constructed, and them play the role of the ``physical'' creation
and annihilation operators. These operators being completed by a ``physical''
vacuum vector give the spectrum of the evolution operator, as well as the trace
of the evolution operator give a correct expression for the partition function.
As an example, Bazhanov -- Baxter's free bosonic model is considered.
