I'm sure by now that everybody knows what happened when the apple fell on Isaac Newton's head. Liz's son knew the answer when he was six. The apple hit him on the head so hard that it made him invent gravity. But there's another side of the story. Have you ever wondered how Isaac felt just before the apple hit him? That vague feeling that you're about to give birth to an idea - all you're waiting for is something to clonk you on the head. Liz has been experiencing all of those feelings lately...