  We employ projection operator techniques in Hilbert space to derive a
continuous sequence of effective Hamiltonians which describe the dynamics on
successively larger length scales. We show for the case of \phi^4 theory that
the masses and couplings in these effective Hamiltonians vary in accordance
with 1-loop renormalization group equations. This is evidence for an intimate
connection between Wilson's renormalization and the venerable Bloch-Feshbach
formalism.
