  We describe an instrument concept that will provide simultaneous spectra for
a million spatial samples on the sky. With the proposed field of view and
spectral resolution, it will be able to measure redshifts and line strengths
for around 2-4000 z~3-7 galaxies in a 16 night campaign. The main science
driver is to obtain a complete census of the star formation properties of
galaxies with 2.5<z<6.7 as a function of luminosity, environment, morphology
and redshift. This survey will also allow us to study the evolution of the 3
dimensional power spectrum and test the connection between these early galaxies
and the large scale structure of the Lyman Alpha forest. Additional science
drivers include [OII] emitters with 0.13<z<1.52, abundance gradients in nearby
galaxies, searches for planetary nebulae in nearby galaxy groups and clusters,
lensed emission line objects, and spectroscopic searches for objects with
continuum breaks. We expect that this instrument will make an ideal partner to
the HST ACS, where ACS morphology and broadband colour information can
complement the MEIFU spectroscopy and help remove any degeneracies in line
identification.
