  We discuss the spectrum of the QCD Dirac operator both at zero and at nonzero
baryon chemical potential. We show that, in the ergodic domain of QCD, the
Dirac spectrum can be obtained from the replica limit of a Toda lattice
equation. At zero chemical potential this method explains the factorization of
known results into compact and noncompact integrals, and at nonzero chemical
potential it allows us to derive the previously unknown microscopic spectral
density.
