  The far infrared background is a sink for the hidden aspects of galaxy
formation. At optical wavelengths, ellipticals and spheroids are old, even at
$z \sim 1.$ Neither the luminous formation phase nor their early evolution is
seen in the visible. We infer that ellipticals and, more generally, most
spheroids must have formed in dust-shrouded starbursts. In this article, we
show how separate tracking of disk and spheroid star formation enables us to
infer that disks dominate near the peak in the cosmic star formation rate at $z
\lapproxeq 2$ and in the diffuse ultraviolet/optical/infrared background,
whereas spheroid formation dominates the submillimetre background.
