  We have obtained a high resolution, high S/N UVES spectrum of the bright QSO
HE2243-6031 to analyze the damped Ly-alpha system (DLA) observed at z=2.33. The
metallicity of this system is 1/12 solar at a neutral hydrogen column density
of log N(HI)=20.7. From the observed ratios [Zn/Cr]=-0.01+/-0.05 and
[S/Si]=-0.06+/-0.03$ we conclude that dust is very likely absent from the ISM
of this protogalaxy. We observe an enhancement of the alpha/Fe-peak ratios of
+0.2 dex for various elements, a marked odd-even effect in Mn, and a strong
underabundance of N relative to Si and S, [N/Si,S]=-1 at [Si/H]=-0.86. All of
these ratios support an environment that is in an early evolutionary stage,
where the onset of star formation has begun only shortly before the DLA was
observed. We also perform a cloud-by-cloud analysis -- without precedent at
high redshift -- and find a tight correlation of all low-ionization species
with respect to FeII extending over 2.5 orders of magnitude in N(FeII). We
interpret this trend as being due to homogeneous physical conditions (very mild
ionization effects, common dust-destruction histories, same chemical
composition) and propose that this line of sight encounters absorbing clouds
that share a common environment. In addition, photoionization models show that
these single clouds are shielded from the external ionizing radiation, so the
fraction of ionized gas is small and, except for argon, does not influence the
measured metal abundances. The observed AlIII/low-ion ratios suggest the mildly
ionized gas occurs in shells surrounding neutral cores of AlII.
