Nothing important happens in life without a cost.

When it comes to solving problems of poverty, impact investing can act as a catalyst, but it is not a silver bullet. Successful businesses serving the poor need more than investment capital. They also need infrastructure to enable effective distribution, strong regulatory systems, access to markets, technical assistance as they scale up, and more

The best change that comes to the world is when all parties are seeing each other as equal, and all parties have the opportunity to be transformed. That really goes back to the idea of dignity.

On the one hand, I loved being a banker. I loved how numbers could tell a story and how you can invest in ideas and see them translate into products and services and create jobs. What I didn't like, particularly where I was working in Brazil during the debt crisis of the early '80s, was how the poor were excluded from the banking system. I made the decision to try and experiment with whether we could use the tools of banking to extend the benefits of the economy to the poor.

There are cases where government-to-government aid actually has worked. Look at the eradication of smallpox and the near eradication of polio. But these are really top down solutions that require government-to-government support and aid.

If you're looking at distributing alternative energy in Nigeria, for instance, what gets in your way is not people's ability to pay, not people's desire for a clean solar lamps or biomass opportunities. But there is a strong status quo that really depends on selling diesel.

A sustainable world means working together to create prosperity for all.