  The diagnostic use and detectability of luminous fine structure lines from
high redshift galaxies is reviewed in the light of results from COBE concerning
the Milky Way and from ISO on low redshift galaxies. At the highest
luminosities (L>10^{12}\Lsun) the [CII] 158 micron line is somewhat less
luminous with respect to the bolometric luminosity than for lower luminosity
objects. Thus, surveys for this line must emphasize depth. The [CII] line will
be the principle spectroscopic probe of the deep universe for the MMA and
FIRST. A deep search for [CII] 158 micron emission from the dusty z=4.693
quasar BR1202-0725 is presented. The resulting 3\sigma upper limit implies that
for this object L[CII]}/LFIR<0.0006%, a highly significant result indicating
that distant luminous objects may represent a natural extension towards higher
luminosities of the ultraluminous infrared galaxies at low redshift.
