Changing how the world operates is hard. Consider Muhammad Yunus, founder of the Grameen Bank (and leader of Bangladesh’s interim government), who brought the idea for lending to the poor to mainstream banks in the early 1980s.The banks challenged Yunus to prove it could work, and he did—first in one town, then five. But still, that wasn’t enough for banks to offer the loans. So, what did Yunus do? He launched the Grameen Bank, and a generation later microfinance—a system of providing small loans to people who otherwise do not have access to conventional banking—has reached every corner of the world, lifting millions out of poverty.