I quite like this as a metaphor for why investing in prevention is a good thing:
Imagine a bucket full of health. This bucket has a hole in the bottom and the health is dripping out (disease). We can mop up the floor below every hour, maybe even squeeze some of the health back into the bucket from the mop. But eventually, the health will be lost because we are not addressing the root of the problem. Instead, we can look for ways to prevent the hole and stop the leak from occurring.
via The Conversation.
Also this use of Prezi to explain the Social Determinants of Health is really impressive.