Picture in your mind’s eye a sprinkler head hooked up to a garden hose. The sprinkler is getting a good supply of water and is reaching all parts of the lawn — that is, until little Bobby comes along.
Little Bobby has discovered that when you poke a hole in a garden hose, you can begin sprinkling other things. When you poke 50 holes, you can sprinkle a lot of other things. And when you place a rock on the hose, you don’t get as much water coming out of all the holes.