  Mensky has suggested to account for "continuous measurement" by attaching to
a path integral a weight function centered around the classical path that the
integral assigns a probability amplitude to. We show that in fact this weight
function doesn't have to be viewed as an additional ingredient put in by hand.
It can be derived instead from the conventional path integral if the
infinitesimal term i\epsilon\ in the propagator is made finite; the "classical
trajectory" is proportional to the current.
