  We show that it is now possible to image optically thick $\lya$ clouds in
fluorescent $\lya$ emission with a relatively long ($\sim 20 $hr) integration
on a large ($\sim 10 $m) telescope. For a broad range of column densities
($N\gsim 10^{18.5} \cm^{-2}$), the flux of $\lya$ photons from recombination
cascades is equal to $\sim 0.6$ times the flux of ionizing photons, independent
of the geometry of the cloud. Additional $\lya$ photons are produced by
collisional excitations when these are the cloud's primary cooling mechanism.
For typical physical conditions expected in optically thick clouds, these
mechanisms together lead to a $\lya$ emission flux that is $\sim (2/3)
\VEV{\nu}/\nu_0$ times the flux of ionizing photons, where $\VEV{\nu}$ is the
mean frequency of ionizing background photons and $\nu_0$ is the Lyman limit
frequency. Hence, measurement of the surface brightness from an optically thick
cloud (known to exist, e.g., from a quasar absorption line) gives a direct
measure of the energy in the ionizing radiation background. Moreover, in the
same long slit spectrum one could hope to detect emission from $\sim 200$ other
$\lya$ systems. Such detections would allow one to make a 2-dimensional map of
the $\lya$ forest. By taking a series of such spectra, one could map the forest
in three dimensions, revealing structure in the high-redshift universe.
