I get a lot of questions about how prayer "works" or whether prayer "works". I think prayer can only not work if we are completely separate. And I believe with Lewis here that our separateness is the real illusion:
Human beings look separate because you see them walking about separately. But then we are so made that we can see only the present moment. If we could see the past, then of course it would look different. For there was a time when every man was part of his mother, and (earlier still) part of his father as well, and when they were part of his grandparents. If you could see humanity spread out in time, as God sees it, it would look like one single growing thing--rather like a very complicated tree. Every individual would appear connected with every other.
-- C.S. Lewis