2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/224883We have conducted a systematic investigation of the origin and underlying physics of the line--line and line--continuum correlations of AGNs, particularly the Baldwin effect. Based on the homogeneous sample of Seyfert 1s and QSOs in the SDSS DR4, we find the origin of all the emission-line regularities is Eddington ratio (L/Ledd). The essential physics is that L/Ledd regulates the distributions of the properties (particularly column density) of the clouds bound in the line-emitting region.to appear in the proceedings of "The Starburst-AGN Connection Conference",ASP Conference Series. Ver2: An appendix of ``Not Baldwin Effect, but ell Effect?'' is added, with two more figures to unveil the nature of the Baldwin effect of AGNsAstrophysics of Galaxiestext