  The propagator of a physical degree of freedom ought to obey a
K\"{a}ll\'{e}n-Lehmann spectral representation, with positive spectral density.
The latter quantity is directly related to a cross section based on the optical
theorem. The spectral density is a crucial ingredient of a quantum field theory
with elementary and bound states, with a direct experimental connection as the
masses of the excitations reflect themselves into (continuum)
$\delta$-singularities. In usual lattice simulational approaches to the QCD
spectrum the spectral density itself is not accessed. The (bound state) masses
are extracted from the asymptotic exponential decay of the two-point function.
Given the importance of the spectral density, each nonperturbative continuum
approach to QCD should be able to adequately describe it or to take into proper
account. In this work, we wish to present a first trial in extracting an
estimate for the scalar glueball spectral density in SU(3) gluodynamics using
lattice gauge theory.
