This is a call to action for the dreamers of the world. Imagine being in a market where more people live in a high-speed mobile Internet zone than have electricity. Where farmers with $50 Android 5.0 smartphones use WhatsApp to joke with their friends on one thread and confirm market prices for cassava on another. And data for one dollar per gigabyte is used to spread viral videos through villages of women singing Michael Jackson. The art of the possible would be different in places like this. The innovative thinking that has defined the world’s best entrepreneurs would be able to create services that don’t exist today that would empower these users. This world doesn’t need imagining — there are many places like this in Sub-Saharan Africa today. Something magical is happening in the poorest countries of the world. With smartphone prices plummeting, with ever-affordable, and fast, mobile data and with increasingly user-friendly services, tech has taken off in Africa. On the other ...