Waterbed theory
Waterbed theory is the observation, ascribed to Larry Wall, that some systems, such as human and computer languages, contain a minimum amount of complexity, and that attempting to "push down" the complexity of such a system in one place will invariably cause complexity to "pop up" elsewhere. This behavior is likened to a waterbed mattress which contains a certain amount of water; it is possible to push down the mattress in one place, but the displaced water will always cause the mattress to rise elsewhere, because water does not compress.