India, Sept. 25 -- In India, we keep a quiet hierarchy of ambition. The brightest young people are steered toward engineering, medicine, management, the careers that promise income and standing. Teaching sits low on that ladder. It is, we tend to assume, a profession of last resort- what a person does when the other doors did not open.

Over the past year I came to know a group of teachers who turn that assumption on its head. They are accomplished women and men who had already walked through the other doors. They were graduates of the country's most competitive institutes and of universities abroad, with lucrative careers in business, technology and the professions. And then they chose, deliberately and at some cost, to leave all of it i...