The blind mage, A problem with targeting? Options

[Karoline]

So, I've seen it come up a couple times before, and was having trouble finding a thread on it (I'm sure there has been), so I figured I'd make a new thread to ask:

Can a blind mage target anything on the physical plane without touching it?

Now, it seems like most people accept that a blind mage can target the physical plane without trouble while astrally perceiving. The problem I have with that is that an aura cannot be used to target something, and there is never anything which states that astral can target a spot on the physical plane by saying 'that spot right there but on the physical plane'.

The closest I can find is

An astrally perceiving
(or otherwise dual natured) magician can cast spells on a
target in either the physical world or in astral space.

but it doesn't specify that you can use astral sight to target something, simply that it is possible to cast a physical spell while perceiving, which can be done via touch spells, or in the case of duel natured creatures, by viewing through their physical senses.

So, is there anything more concrete that says you can in fact use astral sight to target a spell on the physical plane?