Melinda and I read an article about the millions of children who were dying every year in poor countries from diseases that we had long ago made harmless in this country. Measles, malaria, pneumonia, hepatitis B, yellow fever. One disease I had never even heard of, rotavirus, was killing half a million kids each year - none of them in the United States.

We were shocked. We had just assumed that if millions of children were dying and they could be saved, the world would make it a priority to discover and deliver the medicines to save them. But it did not. For under a dollar, there were interventions that could save lives that just weren't being delivered.

If you believe that every life has equal value, it's revolting to learn that some lives are seen as worth saving and others are not. We said to ourselves: "This can't be true. But if it is true, it deserves to be the priority of our giving."

So we began our work in the same way anyone here would begin it. We asked: "How could the world let these children die?"

The answer is simple, and harsh. The market did not reward saving the lives of these children, and governments did not subsidise it. So the children died because their mothers and their fathers had no power in the market and no voice in the system.

But you and I have both.