As Chief Curator of Societal Platform, Sanjay Purohit's role is to bring together, cross-fertilize, and guide an ecosystem of organizations, leaders, and initiatives all dedicated to addressing complex problems at, truly, massive scale. Key lessons: differences between designing for thousands vs. millions of users; focusing platform design on one "core" interaction; empowering networks and organizations that already exist, rather than reinventing the wheel and working in isolation.