From a detailed analysis of higher-order correlations in the 3D distribution of the galaxies from the 2dF galaxy redshift survey, we have measured the bias parameter: i.e., the relation between the clustering of mass and that of galaxies. We conclude that galaxies are unbiased tracers of the mass distribution. This allows us to lift the degeneracy, intrinsic to power spectrum analysis, between the matter density parameter of the Universe and the bias; we thus measure the matter density of the Universe, obtaining Omega(m)=0.27 +/- 0.06. This measurement imposes interesting cosmological constraints e.g., on the amount of dark energy (e.g. cosmological constant) and the amplitude of perturbations.