Muhammad Yunus's New Idea for the Poor

In 2006, the Nobel Laureate Muhammad Yunus, the founder of Grameen Bank in Bangladesh, had what he described as a “casual lunch” with Franck Riboud, the chairman and chief executive officer on the Groupe Danone dairy giant in Paris.

From that lunch has grown an idea perhaps even more radical than microlending, which Yunus developed to transform lending f…