Illusion of Separation: It sounds like a dis/provable proposition. If it is an illusion, you should theoretically then be able to extend the boundary of self and gain greater cognitive perception and influence; or, going the other way, limit your sense of self further and lose control over some of your limbs. But I have never heard of such things occurring. Hence I believe Separation is no illusion at all, but fact, and any experience of greater or smaller consciousness is in fact the illusion.