When I was younger (elementary school age) I would sometimes imagine a white circular shape. If my mind was totally clear of all thoughts and I concentrated on this just right, the circle would expand until all I could "see" was nothing, just whiteness. I would get this really relaxed feeling, like an inner peace. It never lasted that long but sometimes I could achieve it a few times in a row. I haven't been able to do this as I've gotten older. Anyone know what this was?