Why Are AGN So Similar?

AGN display similar continuum and line emission properties over a vast range of 10^8 in luminosity. Their continuum emission most likely originates from accretion disk emission. The continuum of such a disk is expected to show a significant range of peak energy, from 10 eV to about 100 eV, but observations show a small spread in peak energy around 10 eV. In this talk I will describe a mechanism which leads to a uniform SED, without any free parameters. I will also briefly mention the mechanism which likely explains the similar line emission properties.