  We compute complete spectra of the staggered lattice Dirac operator for
quenched SU(3) gauge configurations below and above the critical temperature.
The confined and the deconfined phase are characterized by a different response
of the Dirac eigenvalues to a change of the fermionic boundary conditions. We
analyze the role of the eigenvalues in recently developed spectral sums
representing the Polyakov loop. We show that the Polyakov loop gets its main
contributions from the UV end of the spectrum.
