  We propose a new description of Endofunctors of Module Categories, based upon
a combinatorial category comprising finite sets and so-called mazes. Polynomial
and numerical functors both find a natural interpretation in this frame-work.
Since strict polynomial functors, according to the work of Salomonsson, are
encoded by multi-sets, the two strains of functors may be compared and
contrasted through juxtaposing the respective combinatorial structures, leading
to the Polynomial Functor Theorem, giving an effective criterion for when a
numerical (polynomial) functor is strict polynomial.
