  I will try to put the ultraluminous galaxy phenomenon into a broad
cosmological context. Viewed from this perspective, the significance of
ultraluminous galaxies and the `starburst vs. monster' debate becomes clear.
Ultraluminous galaxies are fascinating in their own right, allow detailed study
of the processes by which massive spheroids were built and the IGM was heated
and polluted, and resemble the most luminous and dustiest galaxies at
high-redshift. Ultraluminous galaxies were apparently far more common at z
$\sim$ 3 than today. Recent inventories in the local universe of the cumulative
effect of nuclear burning (metal production) and of monster-feeding (compact
dark objects in galactic nuclei) imply that either stars or monsters could have
generated the observed far-IR cosmic background. The starburst vs. monster
debate has global, as well as local importance.
