Plato, to make an understatement, comes down on the side of being over seeming. But what can be known, and what is real in this world were questions he explored. One way he approached these ideas was through the story of the prisoners in the cave, and the one who is freed, dragged out into the sunlight and the physical world, and then returns to the cave to try to tell the others that what they think is the world is actually illusion, seeming, not being.
Excellent lecture on The Allegory of the Cave (and more) with creative and animated lecture whiteboard, like an animated "For Beginners" kind of comic.
by Tim Wilson, http://www.zontulfilms.com/
Claymation film of the Allegory of the Cave--with lovely voice over narration reading the text
Some of this sound familiar from other things you've read or seen in movies?