Conservation law of child's blocks analogy In Feynman's Lectures on Physics volume one there is an analogy to conservation of energy (though it would equally apply to other types of conservation). The idea is that if a child has n blocks we should always expect there to be n blocks. We may find the blocks somewhere we do not expect or find blocks from somewhere else, but we should find the n blocks each time. I have seen this analogy ripped of many times. What I want to know is did it start with Feynman or did he rip it off from somewhere else.