 If there is a single notion that plays a role in the rationale of the restriction of composition, it is probably structure. Jaworski probably deploys this notion in the most straightforward way. He and Rea both use the following illustration. If you compact a human being in a machine or waterproof bag, you retain the same matter, but lose the human being, because you have destroyed the structure. Structure is, therefore, a real and essential element in many or most complex objects. He explains his theory as follows. 