Someone on the show speculated that dreams are practice for life. Primitive man might have dreamed of being chased by a bear and what they would do. We may dream of things that could happen now (though I suppose that being chased by a bear is still possible) and how we would deal with it.
It hones our skills and lets us act out events. If you dream that a quilt comes out LOVELY, doesn't that tell yourself that it IS possible and give you the push to achieve what you dreamed?
Just random thoughts for the day. :)