This article on tantra -- Buddhist Tantra - 5 -- says
The deities of the vajrayAna are all manifestations of shUnya. Advayavajra says in a very characteristic verse that the deities are nothing but manifestations of shUnya and are by nature non-existent, and whenever there is manifestation it must be shUnya in essence. The process of evolution of deities from shUnya has four stages: the first is the right perception of the shUnyatA or voidness, the second is its connection with the germ syllable, the third is the conception of an icon and the fourth is the external representation of the deity. This statement which occurs both in the sAdhanamAlA and in advayavajra is a very strong argument against the theory that later Buddhism was nothing but gross idolatry.
They are rather the voluntary manifestations of the shUnya in accordance with the bIjamantras uttered by the worshippers, with an appearance suitable for the function he has to discharge.
Does anyone have the appropiate references to these statements?
