  The aim of this paper is to re-examine the question of the average
magnification in a universe with some inhomogeneously distributed matter. We
present an analytic proof, valid under rather general conditions, including
clumps of any shape and size, and strong lensing, that so long as the clumps
are uncorrelated the average \emph{reciprocal} magnification (in one of several
possible senses) is precisely the same as in a homogeneous universe with equal
mean density. From this result, we also show that a similar statement can be
made about one definition of average \emph{direct} magnification. We discuss,
in the context of observations of discrete and extended sources, the physical
significance of the various different measures of magnification and the
circumstances in which they are appropriate.
