Recent work (Baskin & Laor 2004; Dong et al. 2009a, b) suggests that the Eddington ratio (l ≡ L/L_Edd) is the origin of all the significant first-order object-to-object variations of quasar spectral properties from the zeroth-order similarity of AGN spectra; specifically, this includes the PC1 of Boroson & Green (1992), the classic or inverse Baldwin effect (Baldwin 1977), and even blueshifting (i.e., blue asymmetry) of high-ionization emission lines (Dong et al. 2009c).