  The basic aspects of the momentum picture of motion in Lagrangian quantum
field theory are given. Under some assumptions, this picture is a 4-dimensional
analogue of the Schr\"odinger picture: in it the field operators are constant,
spacetime-independent, while the state vectors have a simple, exponential,
spacetime-dependence. The role of these assumptions is analyzed. The
Euler-Lagrange equations in momentum picture are derived and attention is paid
on the conserved operators in it.
