  In this paper I present evidence suggesting that the absence or presence of
Hidden Broad Line Regions (HBLRs) in Seyfert 2 galaxies is regulated by the
rate at which matter accretes onto a central supermassive black hole, in units
of Eddington. I discuss the above findings in the context of a model proposed
by Nicastro (2000), in which the existence of the BLRs is regulated by the disk
accretion rate. For low enough accretion rates, the disk is stable, and the
BLRs do not form.
