Risen Help with a quest? Beginning of Chapter 3.

Well, i just got the 5 crystal discs, and i've entered the volcano, or w/e it is, and we're trying to get through that massive door, Inquisitor Mendoza has been messing around with a switch thingy for ages, anyway.

I'm upto the part, i have to get through this door to be able to activate the last switch, i can actually see it.. i just cant get through, because of the door, its a big spiky door, like a cage, and in the 2 corners of the room next to the door/gate/thingy, are 2 altars, i have no idea what i'm supposed to put on them? ._.

Generally, when you face such doors with two altars next to them, you're supposed to place something called "Busts" on them - in this case I think they are called Old Busts, it's a golden statue like thing you find. Later on there will be doors looked like this which will require Kings Bust, Priests Bust etc. The naming is just to indicate that you can't use any random Bust. They should be located in the "general area" of the door, so there's no point scouring the world for them.